SCIENCE 10

SECOND QUARTER

L1. ENERGY AND WAVE

What is Energy?

• It is the ability to do work

• It comes in many forms and can transform from one type to another.

• Examples of stored or potential energy include batteries and water behind a dam

• Objects in motion are examples of those having kinetic energy

• Charged particles-such as electrons and protons- create electromagnetic fields when they move, and these fields transport the type of energy we call electromagnetic radiation, or light.

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What are waves?

• Waves are disturbances that travel through either a medium or a vacuum in space (empty space), resulting in vibrations or oscillations.

Can energy be transported?

• Wave is a common term for a number of different ways in which energy is transferred.

How is energy transported?

• Mechanical waves and electromagnetic waves are two important ways that energy is transported in the world around us.

What are mechanical waves?

• are waves that require a physical medium to travel.

• are caused by a disturbance or vibration in matter, whether solid, gas, liquid, or plasma.

• Ex: waves in water and sound waves in air

A medium is a substance (solid, liquid, gas or plasma) that can propagate energy waves.

How are mechanical waves formed?

• Water waves are formed by vibrations in a liquid and sound waves are formed by vibrations in a gas (air).

• These mechanical waves travel through a medium by causing the molecules to bump into each other, like falling dominoes transferring energy from one to the next.

• Sound waves cannot travel in the vacuum of space because there is no medium to transmit these mechanical waves.

Water Waves

• As a wave travels through the waver, the particles travel in clockwise circles.

Sound Waves

• are longitudinal waves because particles of the medium through which the sound is transported vibrate parallel to the direction that the sound wave moves.

• The particles do not move down the tube with the wave; they simply oscillate back and forth about their individual equilibrium positions.

What are electromagnetic waves?

• Electromagnetic waves are waves that can travel through a vacuum (i.e. they do not require a medium).

• are otherwise known as "light waves"

• Gamma rays

• X-rays

• Ultraviolet (uv) waves

• Visible light

• Infrared waves

• Microwaves

• Radio waves

Waves as energy transfer

• In electromagnetic waves, energy is transferred through vibrations of electric and magnetic fields.

• In sound waves, energy is transferred through vibration of air particles or particles of a solid through which the sound travels.

• In water waves, energy is transferred through the vibration of the water particles.

What is an atom?

• An atom is the smallest unit of matter.

• Has a nucleus (which contains protons and neutrons) surrounded by electrons

• All matter consists of atoms in motion and these in turn consist of positively charged protons surrounded by a cloud of negatively charged electrons.

What is produced by a charged particle?

• A charged particle produces an electric field. This electric field exerts a force on other charged particles. Positive charges accelerate in the direction of the field and negative charges accelerate in a direction opposite to the direction of the field.

• An electron generates an electric field which we can visualize as lines radiating from the electron.

What happens when the electron moves?

• If the electron moves, say it vibrates back and forth, then this motion will be transferred to the field lines and they will become wavy.

• In turn, the moving electron generates a magnetic field that will also become wavy from the motion of the electron.

• These combined electrical and magnetic waves reinforce one another. This kind of wave is called an electromagnetic wave.

What produces an electromagnetic wave?

• A charged particle produces an electric field.

• A moving charged particle produces a magnetic field. This magnetic field exerts a force on other moving charges.

• An accelerating charged particle produces an electromagnetic (EM) wave.

• Electromagnetic waves are electric and magnetic fields traveling through empty space with the speed of light c.

Electromagnetic waves consist of both electric and magnetic field waves. These waves oscillate in perpendicular planes to each other and are in phase.

The creation of all electromagnetic waves begins with an oscillating charged particle, which creates oscillating electric and magnetic fields.

Once in motion, electric and magnetic fields that a charged particle creates are self- perpetuating: time-dependent changes in one field (electric or magnetic) produce the other

A group of friends are discussing about who is their favorite scientist in the Electromagnetic Wave Theory

• Guys, for me Ampere is my favorite scientist because he demonstrated the magnetic effect based on the direction of current. Who is your favorite guys?

• Wow, that's a great achievement but Faraday is awesome because he formulated the principle behind electromagnetic induction.

• I like Hertz because he showed experimental evidence of electromagnetic waves and their link to light. Even the unit of frequency is named after him. He is that awesome!

• It's Maxwell who is the most awesome of them. He contributed in developing equations that showed the relationship between electricity and magnetism. He is a brilliant scientist!

• I chose Oersted because he showed how a current carrying wire behaves like a magnet. Without him, the other scientist that you mentioned would not be able to formulate the Electromagnetic Wave Theory.

Proponents on the Formulation of EM Wave Theory

Hans Christian Oersted (1777-1851)

discovered accidentally in 1820 that a magnetic needle is deflected when the current in a nearby wire varies, a phenomenon establishing the relationship between electricity and magnetism.

André-Marie Ampère (1775-1836)

• made the revolutionary discovery that a wire carrying electric current can attract or repel another wire next to it that's also carrying electric current.

• The attraction is magnetic, but no magnets are necessary for the effect to be seen.

• He went on to formulate Ampere's Law of Electromagnetism and produced the best definition of electric current during his time.

Michael Faraday (1791- 1867)

• discovered electromagnetic induction, the principle behind the electric transformer and generator.

•contributed significantly to the study of electromagnetism and electrochemistry

•also made fundamental contributions to the electromagnetic theory of light.

James Clerk Maxwell (1831-1879)

• developed a theory to better explain electromagnetic waves.

•used this field theory to assume that light was an electromagnetic wave, and then correctly deduced the finite velocity of light, it was a powerful logical argument for the existence of the electromagnetic force field.

What does this say about electromagnetic waves?

• Electromagnetic waves in free space can have any wavelength λ or frequency f as long as Af = c.

• The speed of any electromagnetic waves in free space is the speed of light c = 3*108 m/s.

What difference did it make?

• Maxwell's new law and Faraday's law couple together as a wave equation, implying that any disturbance in the electric and magnetic fields will travel out together in space at the speed of light as an 'electro-magnetic' wave..

Heinrich Hertz (1857- 1894)

•German physicist who applied Maxwell's theories to the production and reception of radio waves.

•The unit of frequency of a radio wave - one cycle per second - is named the hertz, in honor of Heinrich Hertz.

•He proved the existence of radio waves in the late 1880s.

•He used two rods that served as a receiver and a spark gap as the receiving antennae. Where the waves were picked up, a corresponding spark would jump.

•Hertz showed in his experiments that these signals possessed all of the properties of electromagnetic waves.

What happened next?

• In 1887 Heinrich Hertz used a spark-gap transmitter and receiver to demonstrate that these waves actually existed.

Electromagnetic waves

• Electromagnetic radiation is a form of energy emitted by moving charged particles. As it travels through space it behaves like a wave, and has an oscillating electric field component and an oscillating magnetic field. These waves oscillate perpendicular to and in phase with one another.

Wave Speed

• how fast a wave travels

• the speed at which the wave moves through the medium

• the speed at which energy is transferred

• depends on the property of the medium

Wavelength 

• The standard unit for all electromagnetic radiation is the magnitude of the wavelength (in a vacuum), which is usually reported in terms of nanometers for the visible light portion of the spectrum.

• Each nanometer represents one- thousandth of a micrometer, and is measured by the distance between two successive peaks.

• the distance between two wave crests (or troughs)

• the length of a whole wave cycle

Frequency 

• how often waves come along

• total number of waves per second

• measured in Hertz

• (1 Hz= 1 cycle/second)

Amplitude

• Distance between origin and crest (or trough)

• The higher the amplitude of a wave, the more energy the wave has.

Relationship between frequency and wavelength

• The frequency of a radiation wave is inversely proportional to the wavelength.

• Short wavelength means lots of waves, and a higher frequency and long wavelength mean fewer waves or a lower frequency.

• Thus, longer wavelengths correspond to lower-frequency radiation and shorter wavelengths correspond to higher- frequency radiation.

The wave speed, wavelength, and frequency of an EM wave are related to each other as shown by the wave equation:

C= A f

• Since c is constant, this means that wavelength is inversely proportional to frequency.

• As the wavelength decreases, the frequency increases and vice-versa.

• Electromagnetic Spectrum- a continuum of electromagnetic waves arranged according to frequency and wavelength.

Mnemonic Device to help you to remember:

• EM Spectrum

• Visible light spectrum 

• The different types of electromagnetic waves are defined by the amount of energy carried or possessed by their photons.

L2. USES OF ELECTROMAGNETIC WAVE

Radio waves

• have the longest wavelengths and lowest frequencies in the electromagnetic spectrum.

Use of Radio waves

1. Radio and television communication (produced by making electrons vibrate in an antenna to create waves that transmit sound and picture information over long distances)

2. Radar & satellite communication - for air traffic control, weather forecasting and navigation

3. Global Positioning System (GPS) - a space-based navigation system that provides geographical position and time information anywhere on or near the earth. It is used for navigation of ships and aircraft

4. Magnetic Resonance Imaging (MRI) - a medical imaging technique that uses powerful magnets, computers, and radio waves to make detailed pictures inside one's body.

Uses of Microwaves

1. Cooking using microwave ovens- microwaves cause water molecules in the food to vibrate, producing heat that cooks the food

2. Radar (Radio Detection and Ranging) communication - a detection system used to determine the range, angle or velocity of objects (as it is not easily blocked by buildings/trees)-can be used to detect aircraft, ships, and the like.

3. Satellite communication because it can penetrate the earth's atmosphere. -An antenna transmits microwave signals to a satellite which amplifies and retransmits the signal to an antenna in other parts of the world.

4. Medical diathermy - treatment prescribed for muscle and joint conditions

5. Terrestrial communication (cable TV, mobile phones)

Infrared waves

• also known as "infrared light".

• encountered every day and detected as heat.

• We often think of infrared as 'heat', because it makes our skin feel warm.

• All objects emit infrared waves because all objects possess heat.

• Many electronic devices use infrared (TV remote control, IR thermometer).

Uses of Infrared (IR) waves

1. Remote control (IR remote) uses LED lights to transmit signals to control devices.

2. Night vision goggles detect IR waves and allow the user to see the movement of objects in the dark

3. Thermal imaging through infrared scanners - used to show the temperature variation of the body which under infrared cameras appear as images in a variety of colors.

• Ex: shades of blue and green indicate regions of colder temperature; and red and yellow indicate warmer temperature.

Visible Light

• only a small part of the EM spectrum but is the only part detected by the human eye.

• enables us to see things around us and gives light to the screen of most electronic devices.

• ex: artificial lights like flashlight, lamp etc. or any light source that produce light instead of the natural light produced by the sun.

• has its own spectrum which consist of the 7 colors of light: Red Orange Yellow Green Blue Indigo Violet

Uses of Visible Light

1. is essential for photosynthesis.

2. used as colorful laser light or the light from a firework.

3. used in optical fibers in medicine (endoscopy) and telecommunications.

Ultraviolet Waves

• UV Light is light at a higher frequency and energy than violet light.

• also produced by electric arcs.

• UV light can kill microorganisms.

• Too much exposure can cause: Sunburn, Wrinkles, and skin cancer as it damages cell DNA

Uses of Ultraviolet Waves

1. UV Lamps are used to check the signature on a passbook, to detect counterfeit currency, passports & other sensitive documents which all contain a uv watermark that is only seen under uv emitting light

2. used in sterilizing water from drinking fountains to remove most forms of microbiological contamination from water

3. to kill insects

4. fluorescence

5. Produces vitamin D in the skin which is essential for maintaining healthy bones and teeth

6. Sun-tanning

7. Sterilize medical equipment

X-rays 

• have high energy and can penetrate some material 

• Soft X-rays can penetrate metals 

• Used in 

• Medicine 

  • CT scans to image injuries from trauma, staging cancer, and diagnosing the condition of the blood vessels.

  • diagnostic tool and dentistry medicine 

• Industry 

  • Industry-wise, it is used to find cracks in structures just like cracks in bones.

• Transportation 

  • Airport security scanners inspect the content of baggage using X-rays.

• Too much exposure can damage living tissue or even cause cancer.

Gamma Rays

• are the highest energy electromagnetic waves.

• They usually come from radioactive elements or stars

• are produced by some radioactive substances and certain nuclear reactions. Because of their great penetrating ability, they can cause serious illness.

• However, their use in controlled conditions is useful in cancer treatment.

Uses include:

1. Killing cancer cells

2. Making pictures of the brain

3. Inspection tools in industry

4. Gamma sterilization of tissue grafts such as bone, cartilage, tendon, ligaments, pericardium, heart valves, and cornea

5. Food irradiation

6. used in medicine for nuclear imaging which enables visualization of organ and tissue structure and function. (ex. renal, thyroid, heart, brain scans.)

7. Radiotherapy (to treat cancer)

8. Inspection tools in the industry (to detect defects in metal castings and to find weak spot in welded structures.)

L3. RADIATION 

What is radiation?

• Radiation is energy that comes from a source and travels through space and may be able to penetrate various materials.

• Also called electromagnetic waves

• It is both natural and manmade and is in two forms: ionizing and non- ionizing.

What are the two types of radiation?

• non-ionizing radiation

• radiation in the ultraviolet band and at lower energies (to the left of ultraviolet).

• does not have enough energy to break chemical bonds or strip electrons from atoms

• ionizing radiation

• radiation at the higher energies to the right of the ultraviolet band.

• carries enough energy to break chemical bonds, knock electrons out of atoms, and cause direct damage to cells in organic matter.

Non-ionizing Radiation (NIR)

• originates from various sources: natural origin (such as sunlight or lightning discharges etc.) and man-made (seen in wireless communications, industrial, scientific, and medical applications)

Types of Non-ionizing Radiation

• optical radiation - can be further subdivided into ultraviolet, visible, and infrared. 

• Electromagnetic fields are further divided into radiofrequency and microwave, static electric and magnetic fields (0 Hz), and extremely low frequency (ELF) fields (>0 Hz to 300 Hz).

• extremely low-frequency (ELF) electric and magnetic fields (EMFs) surround electrical machinery, home appliances, electric wiring, and high-voltage electrical transmission lines and transformers.

L4. RISK OF ELECTROMAGNETIC WAVE

Risk from exposure to radiofrequency (RF) and microwave radiation

• Microwave radiation (MW) is absorbed near the skin, while Radiofrequency (RF) radiation may be absorbed throughout the body.

• At high enough intensities both will damage tissue through heating.

• Sources of RF and MW radiation include radio emitters and cell phones.

• Intense, direct exposure to radiofrequency (RF) or microwave radiation may result in damage to tissue due to heat.

• These more significant exposures could occur from industrial devices in the workplace.

Limiting Radiofrequency (RF) exposure

• Reduce the amount of time spent using the cell phone

• Use speaker mode, head phones, or ear buds to place more distance between the head and the cell phone.

• Avoid making calls when the signal is weak as this causes cell phones to boost RF transmission power.

Infrared

• Sources of IR radiation include furnaces, heat lamps, and IR lasers.

• The skin and eyes absorb infrared radiation (IR) as heat.

• Workers normally notice excessive exposure through heat sensation and pain.

• Medical studies indicate that prolonged IR exposure can lead to lens, cornea, and retina damage, including cataracts, corneal ulcers, and retinal burns, respectively.

• To help protect against long-term IR exposure, workers can wear products with IR filters or reflective coatings.

Visible Light

• The different visible frequencies of the electromagnetic (EM) spectrum are "seen" by our eyes as different colors.

• Good lighting is conducive to increased production and may help prevent incidents related to poor lighting conditions.

• Excessive visible radiation can damage the eyes and skin.

High energy visible light (HEV) or "Blue Light"

• is visible light with wavelengths in the ~381 nm to 500 nm (adjacent to UV on the EMR spectrum)

• exposure is through computers, televisions, and cell phones which can lead to vision loss

• exposure to short-wave light from devices before bedtime may disrupt sleep patterns

• A person who needs protection from Blue Light should secure a lens known as a "blue blocker." Generally, they don't reduce light, but rather, alter the appearance of blue and green colors.

Ultraviolet (UV) radiation

• a form of non-ionizing radiation with beneficial effects that include the production of a vital nutrient, vitamin D (WHO recommends 5-15 minutes of sun exposure 2-3x/wk)

• however, overexposure may present risks such as sunburn, eye damage, premature aging, and skin cancer

• also causes reduced immunity, impaired fertility, and damage to blood vessels.

What are the sources of UV radiation?

• Our natural source includes:

• The sun

• Some artificial sources include:

• Tanning Beds

• Mercury vapor lighting (often found in stadiums and school gyms)

• Some halogen, fluorescent, and incandescent lights

• Some types of lasers

What are the uses of uv radiation?

• production of vitamin D which helps the body to absorb calcium and phosphorus from food and assists in bone development

• Phototherapy using uv lasers/lamps to treat rickets, psoriasis, eczema, vitiligo, lupus

L5. LIGHTS

LIGHT

• Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be perceived by the human eye. Properties of light include reflection, refraction, interference and diffraction.

OPTICS

• Optics is a branch of physics that focuses on the propagation, properties, and behavior of light. It aims to determine the location and characteristics of an image formed by optical instruments, like mirrors and lenses.

REFLECTION OF LIGHT

• Light is an electromagnetic wave and the straight line paths followed by narrow beams of light, along which light energy travels, are called rays.

• Light always travels in straight lines although its direction can be changed by reflection or refraction.

What is reflection?

• the process by which light (and heat) are sent (thrown) back from a surface and do not pass through it (is not absorbed)

REFLECTION OF LIGHT

• Angle of incidence: The angle formed by a ray of light that travels toward a surface and a line perpendicular to the surface.

• Angle of reflection: The angle formed by a ray of light that travels away from the surface and a line perpendicular to the surface. 

• Normal line: The imaginary line perpendicular to the surface of reflection.

LAW OF REFLECTION

• The Law of Reflection states that when light hits a barrier, the angle of incidence is equal to the angle of reflection. This is given by the following equation:

• 0i = 0r

L6. MIRRORS

What is a curved or spherical mirrors?

• a mirror that has the shape of a piece cut out of a spherical surface.

SPHERICAL MIRRORS TERMS

Center of curvature - the center of the sphere of which the mirror is a part

• Its distance form the mirror is known as the radius

Pole (or Vertex) - the center of the spherical mirror  

(P or V).

Principal Axis - the straight line passing through the center of curvature and the pole.

Focus or focal point - the point between the center of curvature and the pole or vertex

Focal length - distance from the pole to the focus.

Types of Mirrors

• Plane Mirror - flat mirrors that reflect images in their normal proportions. Produces virtual image.

• Concave Mirror - are spherical mirrors that curve inward like a spoon.

•  also called converging mirrors because the parallel incident rays converge meet at a focal point after reflection.

• they create the illusion.

• Convex Mirror - are also spherical mirrors, also called diverging mirrors because the parallel incident rays diverge after reflection. 

• However, unlike concave mirrors, they bulge out and distort the reflected image, making it smaller.

Image Formation

All observers would perceive light to be diverging from the same point - the image point.

• An image is a position in space from which all reflected light appears to diverge.

• Image formed by a plane mirror is called a virtual image.

• Virtual images are formed in regions where there is no light.

Image Description

LOST

L - Location

O - Orientation (Erect/Upright or Inverted)

S - Size (Magnified or Reduced/|Diminished)

T - Type (Real or Virtual)

 Image Orientation

1. Upright/Erect - an image in which directions are the same as those of the object. (Patayo)

2. Inverted -  the image is upside down compared to the object. (Baliktad through Y-axis) 

3. Laterally inverted - image is flipped horizontally. (Baliktad through X-axis)

Image Size

1. Enlarged (Magnified) - image is larger than the object. (lumaki)

2. Reduced (Diminished)- image is smaller than the object. (lumiit)

3. Same - image is the same size as the object. (ikaw pa rin)

Image Type

1. Real- image appears in front of the mirror (could be projected onto a screen)

• formed where light rays actually meet after reflection or refraction.

2. Virtual - image appears behind the mirror

• formed where light rays appear to meet after reflection.

Plane Mirror Images

• Located behind the mirror

• Erect or upright

• Same size as the object

• Virtual

• Appears to be at the same distance from the mirror as the object in front of it

• Laterally inverted

4 Principal Rays in Curved Mirror

Uses of Plane Mirror

• Dressing mirror - to see oneself

• Kaleidoscope - a toy that uses lights and mirrors to reflect objects and create beautiful, fascinating patterns.

• Periscopes - an instrument for observation over, around, or through an object, obstacle or condition that prevents direct line-of sight observation from an observer's current position.

Uses of Convex Mirrors

• Side-view mirror - allows the driver to see more objects and a wider view of what's behind.

• Security mirrors - used in malls, convenience stores, and supermarkets to view a large portion of people.

• Camera phone - helps to aim correctly when taking a self-portrait.

Uses of Concave Mirrors 

• Headlights of a car - to produce a parallel beam of light that can be directed down (low beam) or straight ahead (high beam marami nito sa vizal).

• Dentist mirror - focus light on the tooth to be examined to see larger images.

• Make-up/shaving mirrors - enlarges the image

• Headlamps/flashlights -  produces a parallel and brighter beam of light.

L7. LENSES

What is a Lense?

• piece of glass or other transparent substance that is used to form an image of an object by focusing rays of light from the object by refraction.

Convex Lenses

• Thicker in the center than edges.

• Lens that converges (brings together) light rays.

• Forms real images and virtual images depending on position of the object.

Concave Lenses

• Lenses that are thicker at the edges and thinner in the center.

• Diverges light rays

• All images are erect and reduced.

Application of Lenses

• Increasing the focal length in a camera increases the image size.

• Compound microscope - uses several lenses and a light source to greatly enhance the image of the object you are viewing (increase its size).

• Eyeglasses - eyewear used to correct or improve many types of vision problems or refractive errors such as myopia, hyperopia, and blurring due to an irregularly shaped cornea (astigmatism).

• work by adding or subtracting focusing power to the eye's cornea and lens.

• Contact lenses - worn directly on the cornea

• also correct refractive errors.

• also add or subtract focusing power to the cornea and lens.

Example raw ng convex lens is yung mata natin sabi ni maam D

• Vision Correction

• Lenses may be used to adjust the point at which light rays converge on the retina.

• Concave lenses are used to correct nearsightedness (myopia).

• Convex lenses are used to correct farsightedness (hyperopia).

How to draw ray diagrams for lenses?

• Lenses can be drawn as lens shapes or lines.

• The convention is that a diverging lens has inwards arrows and pointing converging lens has outwards arrows, mimicking the shapes of the lenses.

• Draw the optical axis- this is a line through the center of the lens.

• Label the focal point of the lens on the optical axis.

• Label the center of curvature (2F) on the optical axis of the lens.

Rules for Ray in Lenses

Virtual and Real sides of a lens

• Light travels through a lens, unlike a mirror.

• Since light is expected to travel through a lens the real side is on the opposite side of the object.

Ray Diagrams for Concave Lens

• Place the object to the left of the lens.

• The object will be drawn as an arrow to make its vertical orientation obvious.

• The bottom of the object will sit on the optical axis, and the top of the object will sit above the optical axis.

• Draw a ray from the top of the object passing directly through the pole/vertex without any refraction occurring.

• Draw a ray parallel to the optical axis which will be refracted so that its new path is a straight line which, were it to be extended backward, would have passed through the focal point of the lens.

• The point at which these two rays intersect is the location of the image of the top of the object.

Image Description

LOST

L - Location

O - Orientation (Erect/Upright or Inverted)

S - Size (Magnified or Reduced/|Diminished)

T - Type (Real or Virtual)

 Image Orientation

4. Upright/Erect - an image in which directions are the same as those of the object. (Patayo)

5. Inverted -  the image is upside down compared to the object. (Baliktad through Y-axis) 

6. Laterally inverted - image is flipped horizontally. (Baliktad through X-axis)

Image Size

4. Enlarged (Magnified) - image is larger than the object. (lumaki)

5. Reduced (Diminished)- image is smaller than the object. (lumiit)m

6. Same - image is the same size as the object.

Image Type

• Since light is expected to travel through a lens the real side is on the opposite side of the object.

L8. ELECTRIC MOTORS

• turn electrical energy to mechanical energy 

• causing something to move or cause of an object's motion

• Examples: Blender, wheels, hair dryer, blades of fan powered using DIRECT CURRENT (DC) that is produced by cells and batteries

• powered by main electricity uses ALTERNATING CURRENT and ELECTROMAGNETS than permanent

BASIC PRINCIPLES

• works through the principle of electromagnetism

• Electricity in wire creates a magnetic field where it'll have north and south poles (opposite poles attract, like poles repel) . If you surround it with magnet, it will rotate from attractive and repulsive forces

Parts of a Motor

• STATOR

- Stationary part of motor, provides magnetic field

• ROTOR

- Inserted into the stator, consist of copper wire to wrap around axle

• PERMANENT MAGNET

-  The configuration around the plastic drum

- When electric current flows through the coil, the resulting magnetic field pushes against the field created by the stator and makes the axle spin.

• COMMUNICATOR 

- (split-ring) - sits at one end, made of metal ring that is splitted into halves attached to the rotor, it's the one who reverses the direction of current.

- The commutator is necessary because the spinning rotor gets its motion from magnetic attraction and repulsion between the rotor and the stator.

• BRUSHES

-  Made of graphite, found at one end where the rotor exits the motor casing ; it sends the electric current to the communicator

• TERMINALS

- Battery attached to the motor that sends the rotor to spin

• St. Louis Motor (Induction Motor)

- As current runs through a wire, it creates a magnetic field and the magnets on the motor serve to attract and repel the induced magnetic field in the wire. As a result, it spins and the conversion is done.

- in this motor, the Electrodes are connected to the power source 

- brushes are the ones connecting 

electrodes to split ring communicator

TYPES OF MOTOR

ALTERNATING CURRENT MOTORS 

- Found in larger appliances(dishwashing machines, garage door opener, furnaces)

- Consist of stator that supplies coil with A currents, when turned on the attraction and repulsion causes rotor to spin

• DIRECT CURRENT MOTORS

- Have permanent horshoe magnet or stator because it is fixed and coil called armature/rotor because it rotates

- The armature is an electromagnet because a current-carrying wire generates a magnetic field.

- Electricity flows from the positive terminal of battery through circuit to copper brush then to communicator and to the armature.

- But this flow is reversed midway through every full rotation, due to the two gaps in the commutator. 

• GENERATOR 

- Device that converts mechanical energy/motion energy into electrical energy 

- Produces electricity when a coil of wire is wrapped around an iron core and rotated near a magnet.

- Opposite of Electric Motor

- Power stations use generators to supply large scale of electricity

- Used as power back-up

Mechanical Energy is provided by rotating turbines that can be powered by: high pressure steam (nuclear power station, oil and gas), wind, and falling water

• How does wind produce electricity through generator ?

- The wind turns the blades of the 

windmill, known as the turbine, which, 

in turn, spins the shaft that turns the 

coil inside the magnet, known as the 

generator, and it produces the 

electricity

• How does oil and gas produce electricity through generator? 

- Fossil Fuel/Steam/Heat - Oil is burned 

to heat water which makes steam.

- Steam moves the turbine blades that 

turn a shaft inside the generator. 

- The shaft spins the coil of wire inside a 

magnet in the generator that produces 

a current of electricity

• OPERATION INVOLVE 

- Electric current cause magnetism

- The relationship between electricity and magnetism affects the operation involve

• HISTORY OF GENERATOR 

- Came from Oersted, he noticed that a compass needle was deflected when it was near a wire carrying electric 

current and when the direction of the 

current was reversed, the needle 

of the compass moved in the 

opposite direction.

• ELECTRICITY AND MAGNETISM 

- Electricity can create magnetism

- Moving charges create a magnetic field around the wire carrying that current

• PRINCIPLE OF GENERATOR 

- Works on the principle of electromagnetic induction discovered by Faraday wherein he demonstrated that moving a conducting wire back and forth through a magnetic field generated a current. 

- An Electromagnetic Field (E.M.F.) is 

induced in a conductor (i.e. a coil) 

when the magnetic field around it 

changes

- Faraday created the first electricity producing generator, which could 

generate electrical current.

• ELECTROMAGNET 

- A temporary magnet made by wrapping a wire coil carrying a current around an iron core.

- If a soft iron core is inserted into a coil and a current runs through it, then it is an Electromagnet

- When the current turned out, then the EL magnet lose power

- MOST large generators USE Electromagnet than permanent magnets

• PARTS OF A GENERATOR

• STATOR

- Stationary part of motor, provides magnetic field, consist of permanent magnet or Electromagnet 

• ROTOR

- Rectangular or circular rotating  component, include slotted iron laminations which decrease the loss caused by Eddy Current 

• COMMUTATOR 

- Usually made of metal cylinder, split into halves that are attached to the rotor commonly called split-ring that reverse the direction of the current every half turn of the rotor ; works like a rectifier that changes AC voltage to DC voltage within the armature winding; mica sheets help to protect commutator; located on the shaft of the machine

• BRUSHES

- Circular slip rings with sliding contacts to prevent wires from getting twisted; carry induced current out of the coil and responsible for transferring current to the 

external circuit ; the brushes are in constant contact with the 

commutator; the commutator spins while the brushes remain 

stationary, transferring current from the commutator.

•  SHAFT 

– Transfers mechanical energy to

the generator and turns the coil

- Through magnetic field ; may be turned by a turbine that operates with water, steam or air,

or etc

• TYPES OF GENERATORS

• AC GENERATOR (Alternators)

- The most common type 

- Has a coil of wire rotating inside 

- As wires in the coil rotate, electrons begin to move along the wire in one direction but reverse after one half revolution ; The direction of the current from the generator changes twice with each revolution

- The revolution changes every 120 times per second

- Used in houses and powerlines, cars

• DC GENERATORS (Dynamo) 

- The electricity is produced in just one direction 

- Uses split-rings to rotate in only one direction

- Used in batteries, thermocouples

- Used in power stations