# P1

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• Created on: 19-04-14 15:10
What is specific heat capacity?
The specific heat capacity of a material is defined as the amount of energy in joules need to raise the temperature of the material by 1 degree
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Heat transfer equation
Energy= mass x specific heat capacity of water (4200) x temperature change
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What is the difference between heat and temperature?
Temperature is the average kinetic energy of the particles in a substance and heat is the measure of energy
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What is specific latent heat?
The amount of energy (in joules) needed to change the state of 1 kilogram of a substance
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what is convection and conduction?
Conduction is the transfer of heat in solids and convection is the transfer of heat in Fluids (liquids and gases). For instance hot air rises to be replaced by cold air.
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What is a convection current?
Air particules are heated up causing them to vibrate and expand. They are denser than the surrounding particles so rise as the cool the fall. This is a convection current.
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How do you work out payback time?
cost divided by savings per year
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What ways can you insulate your home?
Loft insulation, cavity wall insulation, draught proofing doors and windows and double glazing
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How can you calculate efficiency?
efficiency= useful energy output / total energy input x 100
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What is amplitude?
Maximum height of a wave measured from the middle
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What is wavelength?
Shortest distance between the same point on a different wave (crest to crest
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What is the frequency of a wave?
The number of waves passing a point per second
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How do you calculate wave speed?
Wave speed = frequency x wavelength
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What is the electromagnetic spectrum? (longest to shortest)
Radio waves, microwaves, infrared (IR), visible light, x-rays, gamma rays
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What is the law of reflection?
The angle of incidence is always equal to the angle of reflection
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What is diffraction?
Whenever a wave passes through a gap or moves around an obstacle, they spread out. Maximum diffraction is when the wave is the same size as the gap.
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What is total internal reflection?
When the angle of incidence is big enough all the light stays within the glass. It is reflected internally.
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Uses of total internal reflection?
Fibre optics - used in medicine (endoscope for keyhole surgery), broadband or just transferring lots of information quickly
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What are the uses of lasers?
Surgery, guiding weapons, CD/DVD players and cutting materials
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How does a CD player work?
Laser fired onto CD which has little pits on when it hits a pit theres no reflection and computer chips interprets that to make images and sounds
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How does a microwave heat food?
Microwaves target fat and water molecules then energy is transfered to the rest of the food through convection and conduction
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What is the difference between Analog and digital signal?
Analog is either on or off but analog signal continually changes so digital is easier for devises to interpret.
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## Other cards in this set

### Card 2

#### Front

Heat transfer equation

#### Back

Energy= mass x specific heat capacity of water (4200) x temperature change

### Card 3

#### Front

What is the difference between heat and temperature?

### Card 4

#### Front

What is specific latent heat?

### Card 5

#### Front

what is convection and conduction?