Physics Paper 2 IGCSE

What direction do transverse waves oscillate

Oscillate perpendicular to the direction of energy transfer

What type of waves are electromagnetic waves

Transverse

2 features of transverse waves

1. Can travel in a vacuum

2. Transfer energy & info but not mass

2 examples of transverse waves

1. Ripples on water

2. Vibration in guitar strings

3. EM waves

What direction do Longitudinal waves oscillate

Oscillate parallel to direction of energy transfer

2 features of Longitudinal waves

1. Cannot move in a vacuum

2. Transfer energy not matter

3. Can move in all matter

Example of a Longitudinal wave

Sound waves

How is a short wavelength displayed

Wavefronts are close together

How is a long wave length displayed

Wave fronts are far apart

What is wavelength

Distance from peak to peak

What happens if a wave has a higher frequency

Higher energy transfer

Wave speed equation

Wave speed = frequency X wavelength

Frequency equation

Frequency = 1 / time period

What is the Doppler effect

Change in observed wavelength and frequency of a wave emitted by a moving source relative to an observer

Describe red shift

Galaxies in space emit light waves that look redder to an observer because stars are moving away

5 EM waves

1. Radio

2. Microwaves

3. Infrared

4. Visible Light

5. Ultraviolet

6. X-ray

7. Gamma ray

What EM wave has the highest frequency (shortest frequency)

Gamma Rays

What EM wave has the lowest frequency (longest wavelength)

Radio waves

Uses of Infrared waves

1. Heaters

2. Night vision

Uses of visible light

1. Optical fibers

2. Photography

Dangers of EM radiation

Microwaves - heat damage to internal organs

Infrared - Burns

Ultraviolet - sunburn & blindness

Gamma rays - cell mutations causing cancer

What type of wave is visible light

Transverse

2 things all waves can do

Reflection & Refraction

What is a medium

Material that transmits light

What is the law of reflection

Angle of incidence = Angle of reflection

What happen to the light ray when entering a medium

It bends towards the normal

Equation for refractive index

Refractive index = sin i / sin r

How does total internal reflection occur

Angle of incidence is greater than the critical angle (and the incident material is more dense)

Where is total internal reflection used

1. Optic fibers

2. Prisms

How do you calculate angle size

Sin C = 1 / n

What do Oscilloscopes detect

1. Sound waves

2. An alternating current

What is pitch

The frequency of the vibrating source of the sound waves

(If frequency of vibration is high = high pitch)

(If frequency of vibration is low = low frequency)

What is loudness

The amplitude of the wave

What is the range of human hearing

20Hz - 20,000Hz

What does Brownian motion prove

The air is made up of small particles (invisible to the human eye)

Equation for pressure

P = F / A

What is absolute Zero

Temperature when molecules in a substance have 0 kinetic energy

What does the Kelvin scale start at

Absolute Zero = -273 Celsius

What happens to KE if temperature increases

Kinetic Energy will increase (particles move faster)

What happens in a compressed gas

1. Volume decreases

2. Pressure increases

What happens in a expanded gas

1. Volume increases

2. Pressure decreases

What happens to the KE in a hot gas

Kinetic energy increases

What is the pressure law

Pressure is directly proportional to the temperature

What is Boyles law

Pressure is inversely proportional to volume

What happens when a current is flowed through a coil

Magnetic field is produced

What happens when two magnetic fields interact

A force is produced

How can the direction of the force be changed

1. Reversing current

2. Reversing magnetic fields

How can you increase the force

1. Mag. Field strength increased

2. Increasing current

3. Increasing number of coils

2 characteristics of electric motors

1. Converts electrical to mechanical energy

2. Powered using Direct current

What do the split ring commutators do

Every half revolution they cause the current in the coil to reverse

What energy do loudspeakers convert

Electrical into sound

How do loudspeakers work

1. The changing magnetic field of the coil interacts with the magnetic field. Field of the perm magnet causing coil to vibrate

2. The coil causes the speaker cone to vibrate in step to the original sound

3. Cone causes air to vibrate producing a sound wave

What energy do generators convert

Mechanical into electrical energy

What is electromagnetic induction

When a coil is moved across a magnetic field a current is produced when parallel

What is Faraday’s law

The size of the induced voltage Carl’s ends of a wire is directly proportional to the rate at which magnetic field lines are being cut

2 ways to increase induced voltage

1. Increased speed of movement

2. Stronger electromagnet

3. Increase number of coils

4. Increase coil area

What current is used is dynamos

Direct current

Difference between a dynamo and a alternator

Dynamos - use a split ring commutator

Alternators - use 2 slip rings

How many Hz is the UK mains supply

50Hz

What are transformers used for

To decrease or increase the voltage

What is the main component in a transformer

Iron core

Why is A.C flowed into the primary coil

To produce a magnetic field (and will wither increase or decrease depending on the number of coils in the secondary coil)

Transformer equation

Primary voltage/ secondary voltage = No. of coils on Pr coil / No. of coils on Se coil

3 magnetic materials

1. Steel/ iron

2. Cobalt

3. Nickel

How does magnetic induction work

1. Placing an object in a magnetic field

2. Rubbing a object with a magnet

characteristic of soft materials

They lose/ gain their magnetism easily

3 ways a electromagnet can be made stronger

1. Increasing current

2. Increasing number of coils

3. Using a iron core