Physical World

science year 9 yearly study notes

electrical circuits:

• An electrical circuit is a closed loop that provides a path for the transfer of electrical energy from an energy source to an electrical component. That component then converts the electrical energy into other forms of energy such as light, heat, sound or kinetic energy

circuits must have:

-  a closed pathway, or wires connecting the component to the energy source.

- an energy source such as a power station, generator or battery which causes the current to flow.

-  a component that converts electrical energy into another form of energy and can use the energy to do something useful – for example, a light globe, motor or computer.

An electric circuit has three parts:

• An energy source – like a battery or mains power.

• An energy receiver – like a lightbulb.

• An energy pathway – like a wire. A wire helps to direct the electrons around the device.

• More often than not, electric circuits also contain a switch, which can be used to turn them off and on.

define voltage, resistance and current -

Voltage:

• Voltage is a measure of the amount of energy:

• supplied to the charges by the voltage source (the supply voltage)

• used by the charges as they pass through a component such as a light globe (voltage drop)

• Voltage is measured using a voltmeter. 

• The voltage is high if the electrons are supplied with a lot of energy or are losing a lot of energy. The voltage is low if the electrons lack energy or use very little.

• Voltage is measured in volts (V)

supply voltage:

• electrons get the energy they carry around the circuit from the circuit’s energy source. 

• electrons need to be given energy to ‘push’ them around a circuit. A battery stores chemical energy that is transferred to electrons when the battery's two metal contacts, or terminals, are connected by a circuit.

• higher supply voltages give the electrons a bigger ‘push’ than low supply voltages.

voltage drop:

• electrons lose energy as they pass through a component. This results in a voltage drop across the component. The voltage drop depends on the resistance of the component.

• formula to measure voltage drop or potential difference of a component: V=IR, where I is the current in the circuit and R is the resistance of the component.

Current: 

• is formed whenever charge flows from one spot to another. In an electric circuit, this flow of charge is made up of electrons moving along the wires.

• these electrons and the current they form carry energy around the circuit from the battery to the components.

• current is measured using an ammeter: an ammeter measures the amount of charge that flows through it every second. The current is high if a lot of charge flows in one second and low if only a small amount of charge flows through it.

• current is measured in amperes or amps (A)

Resistance:

• as electrons pass along the wires of a circuit, their path is restricted a little by the atoms that make up the wires.

• resistance measures how difficult it is for current to flow through a material or component. The higher the resistance of a component, the harder it is for electrons to flow through it and the more energy and voltage they lose.

• as the resistance of a component increases, fewer electrons get through it every second, reducing the current flowing through it.

resistance of a wire depends on:

• type of material the wire is made of. Eg. metals have low resistance while rubber has high resistance.

• length of the wire. The longer the wire, the more obstacles the electrons need to pass through, therefore a higher resistance.

• thickness of the wire. The thicker the wire the easier it is for electrons to pass through.

• resistance is measured in ohms (Ω).

identify circuit symbols and draw simple circuit diagrams correctly -

describe how changes in either voltage, resistance or current will affect the behaviour of moving charge in a conductor -

• Current, voltage and resistance are all related to one another. Change one of them and at least one of the others will change too. 

If the:

• Current stays the same, the voltage drop (energy loss) will increase as the resistance increases.

• Supply voltage stays the same but the resistance increases, the current will decrease as less current will flow through the component.

• Supply voltage is increased, the current will increase.

describe the relationship between V, I and R -

• the relationship between current, voltage and resistance can be summarised into Ohm’s Law with states:

voltage = current x resistance (V=IR)

• Ohm’s law can be rearranged to make V, I or R the subject:

V = IR

I = V/R

R = V/I

• For a constant current, the voltage varies directly with the resistance. Eg. if the resistance doubles, the voltage drop will double too.

• For a constant supply voltage, current varies inversely (in the opposite manner) with resistance. E.g. if the resistance doubles, the current flowing with half.

• For a constant resistance, voltage varies directly with current. E.g. if the current doubles, the voltage drop will double too.

identify and explain the behaviour of current and voltage in a series circuit -

• in a series circuit, all the components of the circuit are connected one after the other to form a single loop. 

In a series circuit:

• The current is the same everywhere but the voltage drop across each component varies depending on the resistance of the component. The sum of the voltage drops will equal the supply voltage (total amount of voltage supplied by the battery)

• voltage drop of the battery: V battery = V1 + V2 + V3…

• As more resistance is added (in the form of globes) the total current decreases and the globes glow less bright. Also, if one globe goes out, then all of the globes will stop working.

• The total resistance (also known as the equivalent resistance) of the circuit is the sum of all the individual resistors where:

• R total = R1 + R2 + R3…

identify and explain the behaviour of current and voltage in a parallel circuit -

• a parallel circuit has a number of branches, with each branch having its own components.

In a parallel circuit:

• The current splits at the branches (not always evenly, depends on the resistance). The current across the branches equals the total current of the circuit.

• Adding more globes in parallel has the effect of decreasing the overall resistance of the circuit because the current has more than one option to flow through. This increases the total current.

• The current going into the branches carries the same amount of energy as the battery.

• voltage drop of the battery: V battery = V1 = V2 = V3… (for branches that only have one resistor.)

• The equivalent resistance can be calculated using the following formula:

science notes y9 t2

history of our understanding of atoms -

1808 - John Daltons’ “Billard Ball Model”:

Stated that atoms are solid, invisible and unbreakable spheres. It said that each element has different atoms with different weights and properties. This is because his experiments showed that substances always reacted and combined in fixed ratios based on weight. He thought that this meant each element must have unique atoms that react and combine with each other in simple ratios. 

1904 - Joseph Thomson’s “Plum-Pudding Model”:

This model suggests that each atom was a solid ball of positively-charged material with electrons embedded in it.

1911 - Ernest Rutherford’s “Nuclear Model”:

Rutherford tested the “plum-pudding model” of the atom by bombarding atoms with alpha-particles. These results showed that the alpha-particles went straight through the target atoms. To explain these results, Rutherford suggested that atoms were mostly empty space with a tiny, dense positively-charged nucleus in the middle. Some of the positive particles were deflected back at him supporting the fact that the nucleus was a tiny positive centre.The electrons must orbit the nucleus.

1913 - Niels Bohr’s “Bohr Model”:

Bohr worked out that the electrons in Rutherford's model must be in precise, layered orbits. This arrangement explained ‘spectral lines’ and valency. The model shows that electrons are in precise orbits which have an exact amount of energy. Only a certain maximum number of electrons can fit in each orbit.

1932 - James Chadwick’s Atomic Model:

Chadwick discovered the neutron, showing that the nucleus was not just a mass of positive charge but a cluster of positively charged protons and charge-neutral neutrons.

atomic structure -

• The atomic model is used in science to help us understand the structure of the atom.

• Models are visual representations of difficult to understand/abstract concepts. They enable us to gain a greater understanding of the concept and can be used to make predictions.

• The models used to represent atomic structure have been developed over many decades. The main model used in junior science is the “Bohr Model”. 

properties of subatomic particles -

Protons: 

Relative mass - 1

Charge - +1

Position - nucleus 

Neutrons:

Relative mass - 1

Charge - 0

Position - nucleus

Electrons:

Relative mass - 1/2000 around 0

Charge - -1

Position - orbits around the nucleus in shells

Bohr Model:

Electron arrangement:

• Shell 1 = up to 2 electrons

• Shell 2 = up to 8 electrons

• Shell 3 = up to 8 electrons

• Shell 4 = up to 8 electrons

examples of electron arrangement based on the atomic number -

• Atoms are neutral, which means that they have no charge - there is always an equal number of protons and electrons.

• Atomic number = no. of protons

• Atomic mass = no. of protons + no. of neutrons

• No. of neutrons = atomic mass - atomic number

law of conservation -

‘atoms are neither created nor destroyed during chemical reactions, but rather they are rearranged.’

• A chemical reaction is one where new products are made. Atoms in the reactants are rearranged to form one or more new products.

• Chemical changes are often difficult to reverse.

• e.g. combustion (burning) reactions, release heat and light energy. The products are very different from the reactants.

• Atoms stick together to form different substances. They can either form clusters known as molecules or large grid-like structures known as crystal lattices 

• An element is a substance made up of just one type of atom.

• A compound is made up of atoms from two or more different elements that are chemically bonded together. e.g. carbon dioxide.

• A molecule is made up of two or more atoms. They can be the same or different.

• e.g. oxygen (an element as the atoms are the same) or carbon dioxide (a compound as the atoms are different)

• A mixture can be made up of elements and/or compounds that are separate to each other and can be separated by their physical properties.

• e.g. air is a mixture of gases

structure of the inside of an atom -

• Atoms are made up of subatomic particles known as electrons, protons and neutrons.

• The protons and neutrons form a cluster that sits at the centre of the atom known as the nucleus.

• The electrons are much smaller and lighter and move very fast around the nucleus to form an electron cloud that surrounds the nucleus.

ions -

• Ions are created when atoms either lose or gain electrons to become electrically charged particles.

• If an atom loses electrons, then it has more protons than electrons, giving the atom a positive charge. This positive ion is known as a cation. Metals lose electrons to form cations.

• If an atom gains electrons, then it has more electrons than protons, giving the atom a negative charge. This negative ion is known as an anion. Non-metals gain electrons to form anions.

• The symbol for an ion is the same as the chemical symbol for the atom it was formed from, but with the charge of the atom added to it. E.g. When a sodium atom forms a sodium cation, it gains a charge of +1 so the symbol is Na⁺. The same is true for anions, but the name of the anion slightly changed adding -ide to the end of the atom name.
  
  

ionic compounds -

• Ionic compounds are crystalline structures consisting of oppositely charged ions (positive and negative) attracted to each other by electrostatic attraction.

• They are formed when one atom loses an electron(s) while another atom gains the electron(s).

Once electron transfer has taken place, charged ions remain.

The ions form giant lattices of oppositely charged ions.

• Atoms that lose electrons easily are metals, whereas atoms that gain electrons easily are nonmetals. Therefore, ionic compounds are made up of a metal and a nonmetal.

• When naming ionic compounds formed from 2 elements (in a synthesis reaction) we use the following convention:

• The ionic compound has two parts to its name: a metal and a nonmetal. The metal part is written first followed by the second part which takes the name of the nonmetal but the ending is dropped and replaced with -ide. 

• E.g. A compound made from magnesium and oxygen is called magnesium oxide. A compound made from lithium and chlorine is called lithium chloride.

• We can use the Periodic Table to predict which elements will form ionic compounds. For example, sodium chloride is an ionic compound. You can predict this by looking at the Periodic Table and seeing that sodium is a metal and chloride would have derived from chlorine, which is a non metal gas. Therefore, I can assume that sodium chloride is ionic.

• Other compounds that are ionic can be made from positive metal ions and compound ions. A compound ion is a covalently bonded group of atoms with an overall negative charge. eg, sulfate SO₄^2-, hydroxide OH^-, nitrate NO₃^-, carbonate CO₃^2-.

common ions -

how to make an ionic compound formula -

step 1: write the ions side by side

step 2: draw arrows that cross each other from the ions 

step 3: write the charges of the ions at the end of their respective arrows

step 4: 

a) write the positive ion without its charge

b) write the number of the negative ion as its subscript unless it’s 1

c) write the negative ion without its charge

d) write the number of the positive ion as its subscript unless it’s 1

acids, bases and indicators -

Acids and bases are two groups of compounds.

• Acids are a type of compound that contain hydrogen and can release hydrogen ions (H⁺) into aqueous solutions. They combine with water molecules to produce the hydronium ion, H₃O⁺. They can also be proton (H+) donors. They taste sour and have a pH of less than 7.

• Common acids include hydrochloric acid (found in the stomach), sulfuric acid (used in car batteries), acetic acid (vinegar), citric acid (found in citrus fruits), nitric acid (used to make fertilisers and explosives), phosphoric acid (used to make phosphate salts for fertilisers).

• common properties of acids:

• Are corrosive

• Have a sour taste

• Turn blue litmus paper red

• React with some metals, releasing hydrogen gas and leaving a salt behind

• Conduct electricity 

• Are neutralised by bases, producing water and a salt.

• Bases are a type of compound that, when soluble in water, release hydroxide ions (OH^-) into solution. They can also be proton (H⁺) acceptors. They taste bitter, feel slippery to touch and have a pH of more than 7. If a base can be dissolved in water, it is also known as alkali. The solution it forms is known as an alkaline solution.

• Common bases include sodium hydroxide (drain cleaner), calcium oxide (lime, can be used to neutralise acidic soil), sodium hydrogen carbonate (sodium bicarbonate - used in cooking), calcium carbonate (component of sea creature shells and exoskeletons), magnesium hydroxide (milk of magnesia - used for heartburn or indigestion to neutralise stomach acid)

• common properties of bases:

• Are caustic

• Have a soapy, slimy feel

• Turn red litmus paper blue

• Have a bitter taste

• Conduct electricity

• Are neutralised by acids, producing water and a salt.

• pH is a measure of the amount of hydrogen ions per litre of solution, and is a measure of the acidity or basicity of a substance. The pH range goes from 0 to 14, with each increase by 1 equivalent to a decrease by a factor of 10 in hydrogen ions. It is a logarithmic scale. A strong acid has a pH of 0-2.
  A strong base has a pH of 13-14. Both extremes are very corrosive and these compounds must be treated with caution.

• A weak acid has a pH of around 4.5-6.5. 

• A weak base has a pH of around 8–10

• A neutral substance has a pH of 7.

• The chart below shows the pH scale using the universal indicator. The indicator changes a different colour with each increase in pH number.
  

• Indicators are substances that change colour over a particular pH range when they are placed in acidic or basic solutions. They are used to determine approximately how acidic or basic a substance is.  

• They can be natural substances like red cabbage juice or chemicals such as bromothymol blue or phenolphthalein, which are weak acids or bases themselves.

• common indicators:

• Phenolphthalein

• Methyl orange

• Methyl red

• Litmus

• Bromothymol blue

chemical and physical changes -

Physical change: A physical change is a change in the state or appearance of a substance, without forming a new substance.

Key Features:

• No new substance formed.

• Usually reversible.

• Changes in state, shape, or size.

Examples:

• Melting ice → water (solid to liquid)

• Boiling water → steam (liquid to gas)

• Dissolving sugar in water

• Crushing a can

Chemical change: A chemical change results in the formation of one or more new substances with new chemical properties.

Key Features:

• New substance(s) formed.

• Often irreversible.

• Observable signs (may include):

  • Color change

  • Gas production (bubbling/fizzing)

  • Temperature change (exothermic/endothermic)

  • Precipitate formation (solid forming in solution)

  • Light or sound produced

Examples:

• Burning magnesium → magnesium oxide

• Iron rusting → iron oxide

• Vinegar + baking soda → fizzing from CO₂ gas

• Acid + base → salt + water (neutralisation)

common signs of chemical reactions -

the periodic table -

1. Arrangement by Atomic Number:

• Elements are arranged in order of increasing atomic number (the number of protons in the nucleus). 

• This order reflects the increasing number of electrons in the atom, which dictates the element's chemical behavior. 

2. Groups (Vertical Columns):

• Elements within the same group share similar properties because they have the same number of valence electrons (electrons in the outermost shell). 

• Valence electrons are the ones involved in chemical bonding. 

• Groups are numbered 1-18 from left to right. 

• Some groups have common names like alkali metals (Group 1), alkaline earth metals (Group 2), halogens (Group 17), and noble gases (Group 18). 

3. Periods (Horizontal Rows):

• Elements in the same period have the same number of electron shells. 

• As you move across a period from left to right, the number of electrons increases, leading to a change in properties. 

• There are seven periods in the periodic table. 

4. Periodic Law:

• The periodic law states that the properties of elements are periodic functions of their atomic numbers. 

• This means that certain properties (like electronegativity, metallic character, and ionization energy) show predictable trends as you move across the table. 

5. Metal, Nonmetal, and Metalloid Classification: 

• The periodic table can be broadly divided into metals, nonmetals, and metalloids (also known as semi-metals).

• Metals are generally located on the left side, nonmetals on the upper right, and metalloids along a diagonal line separating them.

• Metals have characteristics like being lustrous, good conductors of electricity, and ductile and malleable, while nonmetals are often brittle and poor conductors. 

6. Key Trends:

• Electronegativity:
  - Generally increases from left to right across a period and decreases down a group. 

• Metallic Character:
  - Generally decreases from left to right across a period and increases down a group. 

• Atomic Size:
  - Generally decreases from left to right across a period and increases down a group. 

Heat energy:

The particle model -

• Heat is a form of energy that can be transferred through solids, liquids, and gases.

• In a solid, the particles are closely packed together. They vibrate on the spot but keep the shape of the substance they form.

• Particles in liquids are packed closely as well. They vibrate but are also free to move or flow over each other.

• Gas particles are not bound together at all and are free to move in straight lines until they collide with other gas particles or the walls of a container. 

• Heating a substance adds energy to its particles. Some of the energy is stored in the material as potential energy, while the remaining heat energy increases the kinetic energy of the particles in the material. 

• If the temperature of a substance increases, its particles move faster. This spreads the particles further apart, causing it to expand. If the temperature of a substance decreases, its particles lose kinetic energy, causing it to contract. 

• When enough heat energy is added to a solid or liquid, the particles break free from each other, causing the substance to change states

Heat transfer - Heat flows from areas of high temperature to areas with low temperature. The greater the temperature difference, the faster the flow of heat. This can occur in 3 ways: conduction, convection, and radiation.

Conduction -

• Hotter substances have particles that are moving faster than particles in cooler substances. The process of heat transfer by vibrating particles is known as conduction.

• Example: When a metal spoon is put into a bowl of hot soup, the vibration of particles in the soup makes the particles in the spoon vibrate faster as well, increasing the temperature of the spoon. This vibration of particles is passed on from one particle to the particle next to it, and this process continues along the spoon.

• Conductors: Substances that transfer heat easily. For example, metals, particularly copper, silver, gold, and aluminium. 

• Insulators: Poor conductors of heat. For example, plastic, air, cloth, cork, wood, rubber. 

Convection -

• As air is heated, its particles gain energy and move further apart. This hot air is less dense than cool air, so it is pushed upwards by the cooler air around it. This method of heat transfer is called convection. 

• The air flow it creates is called a convection current. Heat is transferred by convection in liquids and gases because their particles can move around, rather than remaining fixed like those in a solid. 

Radiation - 

• The process where the Sun transfers its heat energy. 

• Radiation transmits heat as invisible waves that travel at the speed of light (around 300 000 km/s). Infrared radiation is heat energy that is transmitted this way. All objects emit some infrared radiation. 

• The hotter something is the more heat it radiates. 

• When radiated energy hits a surface, the heat can either be absorbed into the surface, reflected from the surface, or transmitted through the surface. 

• Dark colours absorb radiated heat, light colours reflect radiated heat, clear materials transmit radiated heat. 

Sound:

• Sound is produced when something vibrates very quickly. When something vibrates, it passes the vibrations into its surrounding environment, such as air. 

• The vibration creates regions of space in which the air particles are bunched together called compressions and regions in which they spread out called rarefactions. 

• A sound wave is the movement of alternating compressions and rarefactions. 

• A sound wave relies upon particles that vibrate for it to be transmitted. Therefore a solid, liquid, or gas is needed for a sound to be produced. 

Types of waves - 

• A wave carries energy from one point to another.

• The energy carried by waves at the beach moves horizontally, but the particles that make up the wave move in a vertical direction. This type of wave is called a transverse wave. Radiated heat energy is transferred as a type of transverse waves. In a transverse wave, particles move at right angles to the direction of the movement of the wave.

• A sound wave is a longitudinal wave or compression. In longitudinal waves, particles move in the same direction that the wave is moving. 

Transmission of sound -

• Sound energy is transmitted through a material as longitudinal waves. The particles of the material vibrate as the sound energy flows through it.

• The speed at which sound transmits through a material depends on the material that it is traveling through. In general, the more closely packed the particles are in the material, the faster the series of compressions and rarefactions will travel. As a result, sound travels faster through solids than liquids, and faster through liquids than gases. 

• The temperature of the material also affects the speed of sound. The particles of warmer materials vibrate faster than particles in cooler materials. As a result, sound travels faster through warm air than cool air, and faster through warm water than cold water.

Reflection and absorption of sound - 

• Hard surfaces such as concrete reflect sound waves. This reflected sound is heard as an echo. 

• Soft materials such as cushions absorb sound and convert it into heat. This reduces the reverberation, or length of time a sound is heard.

Frequency and pitch -

• A source that vibrates rapidly produces sound of a higher pitch, or frequency, than one that vibrates slowly. 

• The number of vibrations a sound makes each second is called the frequency of a wave. Frequency is measured in hertz (Hz). The wavelength of a sound is the distance between successive peaks. It is measured in meters. 

• Louder sounds have larger peaks, meaning they have greater amplitude than softer sounds. 

• Sounds with higher frequency produce sound waves that are shorter in wavelength with the compressions and rarefactions bunched closer together. 

• Sounds with low frequency produce sound waves with wider-spaced compressions and rarefactions, resulting in a larger wavelength. 

Light:

• Light is a form of energy called electromagnetic radiation. It travels as an electromagnetic wave. 

• Like a sound wave, an electromagnetic wave has a specific wavelength and frequency. It does not need a material to transmit through, and can pass through a vacuum of empty space. 

• Speed of light: 300 000 m/s

• When light hits a surface it may be: transmitted, reflected, or absorbed.

• Any object that emits light is known as luminous. However, most objects do not produce light, rather they reflect it. 

Diffuse and regular reflection - 

• Regular reflection occurs when light reflects off a very smooth substance such as a mirror or window. This produces a clear image. 

• The surfaces of most objects are quite rough when viewed up close. These surfaces reflect or scatter light in many directions and do not form an image. This is called diffuse reflection. 

The law of reflection: An incoming ray of light, known as an incident ray, is reflected off a mirror at the same angle. A dotted imaginary line, called the normal, is shown at right angles to the surface of the mirror. This is used to measure the angle of incidence and the angle of reflection. 

Refraction - 

• Refraction is the bending of light as it passes from one medium to another. 

• Light refracts when it travels from one transparent substance into another. 

• Why does it happen? Light travels at different speeds through different substances. The differences in its speed result in different amounts of bending, as the light passes. The refractive index is a measure of how easily light travels through a substance. The smaller the refractive index of a material, the faster light will travel through it. The higher the refractive index of a substance, the more light bends when it enters the substance from the air. 

• The angle that the refracted ray makes with the normal is called the angle of refraction.

Convex lens:

• Thicker in the middle, thinner at the edges.

• Bends light rays toward the centre (they converge).

• Used in magnifying glasses, cameras, microscopes, the human eye, and projectors.

• Can form real or virtual images depending on the object’s distance.
  
  

Concave lens:

• Thinner in the middle, thicker at the edges.

• Bends light rays outward (they diverge).

• Used in glasses for short-sightedness (myopia), peepholes, and some optical instruments.

• Always forms a virtual image (upright and smaller).

Waves:

Properties and types of waves:

• A wave is disturbance that travels through a medium (matter) from one location to another

• It is a transfer of energy without moving matter

• This disturbance is known as a Propagation

Longitudinal Waves:

A longitudinal wave is a wave where the direction of propagation is parallel to the direction of travel of the medium particles. These waves have two main components within them:

• Compressions - These are areas where the particles are compressed close together in the wave. This is what causes the transfer of energy, as the compressions make the medium move quickly back and forth, pushing the particles ahead to create further compressions.

• Rarefactions - These are areas where the particles pull away from each other in the wave. This reaction is caused after a compression is taken place, and the vibrations pull the particles back together after pushing them, creating the rarefactions. 

Common examples of longitudinal waves are Sound waves, Ultrasound waves and seismic P-waves. This is a form of mechanical wave, which requires a medium.

Transverse Waves:

A transverse wave is a wave where the direction of particle movement is perpendicular to the direction of propagation. These also have two main components, Crests and troughs:

• Crests - The crest of a transverse wave is the highest point of displacement of the wave which is perpendicular to the direction of travel.

• Trough - The trough of a transverse wave is the lowest point of displacement of the wave which is perpendicular to the direction of travel.

Common examples of transverse waves are water ripples, electromagnetic waves and s-waves. These types of waves do not require a medium in some cases such as when they are electromagnetic waves.

Definitions:

• Amplitude - The maximum distance it extends beyond its middle position. Maximum displacement of a vibrating point based on an equilibrium position. In a transverse wave, it is the distance between the equilibrium point (the middle line) and the crest or trough. In a longitudinal wave, it is the position from the equilibrium position (the middle of the compression lines) to the rarefactions starting point. The larger the amplitude, the more energy is carried in the wave.

• Wavelength - The distance between 2 successive waves, measured in meters. This is the difference between two points on the same phase of the wave. This can be crest to crest or trough to trough in transverse waves, and start of compression to start of compression in Longitudinal waves.

• Period - The amount of time it takes in second for 1 wavelength to pass through a given point

• Frequency - The number of wavelengths that pass through a single point within one second. It’s measured in hertz

• Velocity - The speed of the energy transfer measured in meters per second

The wave equation:

• The speed, frequency and wavelength of a wave are joined by an equation. If the frequency of a wave increases, the wavelength will decrease. If the frequency of a wave decreases, the wavelength will increase.

• Speed = frequency x wavelength

• Frequency = speed / wavelength

• Wavelength = speed / frequency

Components of an ecosystem: