# Physics Unit 1 Revision

In which 3 ways can heat be transferred?
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What substances can emit infrared radiation?
Solids, Liquids and Gases
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What happens to speed of infrared radiation if there is a bigger temperature difference?
The faster energy is transferred by heating
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What surfaces are good at emitting and absorbing infrared radiation?
Dark, matt surfaces are much better than light shiny surfaces (reflects)1
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Kinetic Theory - Solids
Strong forces of attraction hold the particles close together in a fixed regular arrangement. The particles don't have much energy so they can only vibrate in their fixed position
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Kinetic Theory - Liquids
Weaker forces of attraction between the particles. The particles are close together, but can move past each other, and form irregular arrangements. They have more energy than the particles in a solid (move in random directions at a low speed)
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Kinetic Theory - Gases
Almost no forces of attraction between the particles. The particles have more energy than those in liquids and solids (free to move) and travel in random directions at high speeds
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What happens to the particles when you heat a substance?
They vibrate or move faster
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What does the rate at which an object transfers energy by heating depend on?
Surface area and volume. The material from which the object is made. The nature of the surface with which the object is in contact
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What do U-values measure
How effective an insulator is
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If a material is a good insulator will the U-value be low or high?
Low
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How do solar pannels work if they contain water?
The water is heated by the radiation from the sun. This water may then be used to heat buildings or provide domestic hot water
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Definition of specific heat capacity
The specific heat capacity of a subatnce is the amount of energy required to change the temperature of one kilogram of the substance by one degree celsius.
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The equation of specific heat capacity
E = m x c x
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What can and can't be done with energy?
Can be transferred usefully, stored or dissipated. But cannot be created or destroyed
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What happens to the rest of the energy when only some of it is usefully transferred?
The rest is 'wasted'
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Efficiency Calculation
Efficency = useful energy out/total energy in (x100)
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What does the amount of energy an appliance transfers depend on?
How long the appliance is switched on and its power
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How to calculate the amount of energy transferred from the mains?
E = P x t
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Units of mains electricity
cost per kilowatt-hour
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In some power stations an energy source is used to heat water. The steam produced drives a turbine that is coupled to an electrical generator. What do the energy sources include?
Fossil Fuels which are burned to heat water or air. Urainium and Plutonium, when energy from nuclear fission is used to heat water. Biofuels that can be burned to heat water
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How is electricity distributes from power stations to consumers
The National Grid
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For a given power increasing the voltage reduces what?
The current required and this reduces the energy losses in the cables
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What transfers energy?
Waves
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Waves can either be?
Transverse or Longitudinal
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Examples of each kind of waves?
Electromagnetic waves are transverse. Sound waves are longitudinal. Mechanical waves may be either transverse or longitudial.
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What happens to all types of electromagnetic waves as they travel through a vaccum(space)?
Travel at the same speed
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What do longitudinal waves show?
Areas of compression and Rarefaction
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Waves can be reflected and refracted but can they be diffracted?
Yes
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What happens to a wave when they're refracted at an interface?
Undergo a change of direction
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What waves can be used for communication?
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What is the amplitude of a wave?
The displacement from the rest position to the crest
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Wavelength?
Crest to Crest
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Frequency?
The number of complete waves passing a certain point per second (1 Hz is 1 wave per second)
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Transverse waves
The vibrations are perpendicular to the direction of energy transfer of the wave
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Longitudinal waves
The vibrations are parallel to the direction of energy transfere of the wave
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Wave Speed =
Frequency x Wavelength - v = f x
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Name the waves in the EM Spectrum
Radio waves, Micro waves, Infra Red, Visible light, Ultra Violet, X-rays, Gamma rays
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What does the angle on incidence =
The angle of incidence = The angle of reflection
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Describe the image formed in a plain mirror
Virtual, Upright and Laterally Inverted
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What are sound waves?
Longitudinal waves and cause vibrations in a medium detected as a soudnd
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What is the pitch determined by?
Frequency
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What is the loudness determined by?
Amplitude
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What is an echo?
Reflections of sound
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What is the doppler effect?
If a wave source is moving relative to an observer there will be a change in the observed wavelength and frequency
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What is red-shift?
There is an observed increase in the wavelength of light from most distant galaxies. The further away the galaxies are, the faster they are moving, and the bigger the observed increase in wavelength
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What is Cosmic Microwave Background Radiation?
It's a form of electromagnetic radiation filling the universe. It comes from radiation that was present shortly afer the beginning of the universe.
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What is the only theory that can explain the existence of CMBR?
Big Bang
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## Other cards in this set

### Card 2

#### Front

What substances can emit infrared radiation?

#### Back

Solids, Liquids and Gases

### Card 3

#### Front

What happens to speed of infrared radiation if there is a bigger temperature difference?

### Card 4

#### Front

What surfaces are good at emitting and absorbing infrared radiation?

### Card 5

#### Front

Kinetic Theory - Solids