Physics Unit 1 (P1)

Front 1

What factors affect the emitting and absorbing of energy?

Back 1

How much energy is transmitted depends on the temperature and the colour of the material.

Energy may be transferred by infrared radiation. This is a type of electromagnetic wave. It can travel though vacuum such as space, without the need for particles.

Front 2

What is emission, and what are good emitters?

Back 2

Emitting is giving out.

Hotter objects emit more infrared radiation than cooler ones. This is why people show up as bright colours on infrared cameras compared to the darker, cooler surroundings.

• Dark, matt surfaces are good emitters of infrared radiation.
• Light, shiny surfaces are poor emitters if infrared radiation.

Front 3

What is Absorption, and what are good absorbers?

Back 3

Absorption is taking in.

• Dark, matt surfaces are good absorbers of infrared radiation
• Light, shiny surfaces are poor absorbers of infrared radiation

A matt black surface is a good absorber of infrared, so heats up quickly. Instead of absorbing infrared radiation, shiny surfaces are good reflectors. This means they don't heat up as fast.

Front 4

What is the difference in the arrangement of particles between solids, liquids, and gases?

Back 4

Solids: Particles are regularly arranged, close together, and they are not able to move around, only vibrate.

Liquids: Particles are a little bit further apart, they are able to move around.

Gases: Particles are very far apart and move very fast.

Front 5

What is kinetic theory?

Back 5

Kinetic theory can be used to explain different states of matter in terms of particles.

Front 6

List the particle energy of solid, liquid and gas in order of least to most energy.

Back 6

The particles in solids and liquids and gases have different amounts of energy.

The order from least to most energy is:

Solids - Liquids - Gases

The particles in gases have most energy because they are moving the fastest. The particles in solids have the lowest energy.

Front 7

What happens to the particles if you increase the temperature of a substance?

Back 7

If you increase the temperature of a substance, the particles gain more energy and move faster. This causes solids to turn to liquids and then eventually gases.

Front 8

What are the four ways energy can be transferred from hotter objects to cooler surroundings.

Back 8

Energy can be transferred from hotter objects to cooler surroundings by

• conduction
• convection
• evaporation
• condensation

This cools the hotter objects and at the same time warms up the surroundings.

Front 9

Where does conduction take place and how does it work?

Back 9

Conduction takes place in solids. When one end of the solid is heated the particles in the solid gain energy and vibrate more.

The vibrations are passed on to neighbouring particles and energy transferred through the solid.

Front 10

What are the best thermal conductors and why?

Back 10

Metals are the best thermal conductors because metals contain free electrons, which are able to move within the metal. These transfer faster through the metal.

Front 11

Why are liquids and gase thermal insulators?

Back 11

Particles in liquids and gases are too far apart to be good thermal conductors. Liquids and gases are thermal insulators.

Front 12

What is convection and where is the only place it can happen?

Back 12

Convection can only take place in fluids (liquids and gases). In convection particles must be free to move. In a solid the particles are fixed, so convection cannot take place.

Convection occurs when part of the fluid is heated:

• The particles in that region gain kinetic energy and speed up.
• The region expands as the particles move further apart.
• This makes this part os the fluid less dense and it rises.

In convection, hotter regions of fluid rise through colder ones. This transfers energy from hotter regions to cooler ones.

Front 13

What is evaporation and how does it work?

Back 13

Evaporations has a cooling effect on liquid. As a liquids starts to evaporate, the particles with the most energy leave the liquids and turn to gas. This transfers energy away from liquid and so it gets cooler.

There are three main ways to increase the rate of evaporation:

• Increase the surface area of the liquid.
• Pass an air current over the surface.
• Increase in the temperature of the liquid.

Front 14

What is condensation and how does it work?

Back 14

Condensation is the the reverse of of evaporation. When a warm gas strikes a cooler surface the gas turns into a liquid. The temperature of the surface increases as some of the energy from the gas particles is transferred to it.

Front 15

What factors affect the rate of energy transfer?

Back 15

• The objects surface are and volume
• The material from which the object is made
• The nature of the surface that is in contact with the object.

Front 16

Name 3 features of a vacuum flask that minimise energy transfer.

Back 16

Vacuum layer inside the glass vessel - prevents conduction and convection.

Shiny silver on both the inside and outside of the glass vessel - poor emitter if IR and a good reflector.

Tight screw cap - reduces convection and evaporation

Front 17

What are 3 techniques of insulating your home, and how do they work?

(Need to be detailed for full marks)

Back 17

• Cavity-wall insulation: a material in between the walls that traps air in pockets, reducing conduction and preventing convection.
• Loft insulation: works in the same way as cavity-wall insulation. A material in the loft that traps air, reducing conduction and preventing convection.
• Double glazing: conduction is reduced by a layer of air or gas trapped between two panes of glass.
• Draft excluders: energy loss through convection is reduced by making it more difficult to set up convection currents.
• Curtains: reduces energy loss through radiation and conduction, by reducing the energy transfer to the windows.

Front 18

What are U-values, and what do they show?

Back 18

U-values measure how effective a material is as an insulator.

The lower the U-value the better an insulator

Front 19

What is payback time, and what is the equation for working it out?

Back 19

Payback time is the time taken to recover the amount of money paid out in making a change from the resultant saving in energy bills

The equation is:

Payback time = Cost / Savings per year

Front 20

Explain the use of solar panels and how they work?

Back 20

Solar panels contain water that is heated by directly by infrared radiation from the sun. The infrared radiation is absorbed by the panel and is transferred to water passing through it. This reduces the cost of heating the water.

Front 21

Explain what is meant specific heat capacity?

Back 21

The specific heat capacity of a substance is the amount if energy required to change the temperature of 1kg of the substance by 1'C.

Different materials have different specific heat capacities. An object with low specific heat capacity does not take much energy to increase its temperature. An object with a high specific heat capacity requires more energy to increase the same mass of substance by the same temperature.

Front 22

What is the equation for specific heat capacity?

Back 22

The equation is:

E = m x c x ⌀

Energy transferred = mass x SHC x CIT

SHC = Specific heat capacity

CIT = Change in temperature

Front 23

What are applications for specific heat capacity?

Back 23

Water: High specific heat capacity which makes it useful for coolant in engines. It can also absorb a lot of energy.

Electrical storage heaters: These contain large blocks of concrete. These have high specific heat capacity. They slowly absorb energy at night, transferring it into the surroundings during the day.

Oil-filled radiators: Rather than heat the air directly, oil inside the radiator is heated. This stores lots of energy in the oil which is slowly transferred to the surroundings.

Front 24

What is the law of conservation of energy?

Back 24

The law of conservation of energy is one of the most important rules in all of physics. It states:

Energy can be transferred usefully, stored, or dissipated but cannot be created or destroyed.

Front 25

Name 7 forms of energy?

Back 25

• kinetic
• sound
• light
• heat/thermal
• electrical
• gravitational potential
• elastic potential
• chemical
• nuclear

Front 26

How is energy wasted?

Back 26

Since energy cannot be destroyed, then the term wasted refers to energy that has been transferred to a form or forms that we no longer require.

For example, the heat energy from a light bulb is not usually needed; it can be described as wasted energy.

Front 27

Explain what a sankey diagram is and how it is used.

Back 27

Energy transfers can be represented as special arrowed diagrams called sankey diagrams.

These not only show the energy transfers but how much energy is transferred into each type. The thicker the arrow the greater the proportion of energy transferred into this form.

Remember, energy cannot be created or destroyed. So the total energy must stay the same.

Front 28

What is meant by energy efficiency?

Back 28

The amount of energy transferred into useful forms, compared to the amount put in.

Efficiency is measured as a percentage or decimal. For example, a washing machine might be 40% or have an efficiency of 0.4. This means that is transfers 40% of the energy going into it into useful forms. Which means 60% of the energy is wasted.

Front 29

What is the equation for efficiency?

Back 29

The key equation for working out efficiency is:

efficiency = useful energy transferred

total energy supplied

Front 30

How are sankey diagrams used to present efficiency?

Back 30

You can compare the efficiency of devices using the information in a Sankey diagram.

The greater the size of the useful arrow, the more efficient the device.

Front 31

Name 3 electrical devices, the energy put in, and the main forms of energy given out.

Back 31

Device - energy in - main forms of energy out

Kettle - electrical - heat, kinetic

Toaster - electrical - heat, light

Electric motor - electrical - heat, sound, kinetic

Speaker - electrical - sound, kinetic

Computer - electrical - heat, light, sound, kinetic

Front 32

What are the two factors that affect the energy transferred by an electrical device?

Back 32

The amount of electrical energy transferred by an electrical device depends on two factors:

• how long the device is used for
• the power of the device

A more powerful device may be used for a shorter time and so may use less energy than a less powerful device.

Front 33

What is the equation used to calculate the power of a device?

Back 33

E = P x t

E = electrical energy transferred (joules, J)

P = power of device (watts, W)

t = time used for (Seconds, s)

Front 34

Why is it good to reduce energy consumption and what are two methods of doing this?

Back 34

It is important to try to reduce our energy consumption. This not only saves us money, but it also conserves out natural resources and means less electricity needs to be generated.

There are several ways of doing this:

• Replace inefficient filament bulbs with low-energy lighting. Such as, compact fluorescent bulbs or LEDs
• Replacing older electrical devices with more modern, energy efficient ones.

Front 35

What is a kilowatt-hour (kWh)?

Back 35

This is a unit of energy

One kWh is the same as 3/6 millions joules.

Front 36

What is the equation for the energy transferred by a device?

Back 36

E = P x t

E = Electrical energy (kilowatt-hours, kWh)

P = Power of device (kilowatts, kW)

t = time used for (hours, h)

Front 37

What is the equation for calculating the cost of electricity?

Back 37

Cost = Cost per kWh x energy transferred

Cost = Pence per hour, p

Cost per kWh = pence per kilowatt-hour, p/kWh

Energy transferred = kilowatt-hour, kWh

Front 38

How is electricity generated?

Back 38

A generator is used and this converts kinetic energy into electrical energy. The generate electricity all you need to do is make a generator spin.

Front 39

Explain how a thermal power station works?

Back 39

• Water is heated, turning into steam
• The steam turns a turbine
• The turbine turns a generator
• The generator transfers kinetic energy into electrical energy.

Front 40

What is a start-up time?

Back 40

The delay between starting a power station and it generating electricity.

Different types of power station have different start-up times. This is how quickly they can increase or reduce the amount of electricity they are generating. Nuclear and coal have slow start-up times but natural gas and hydroelectric are much quicker.

Front 41

What is a pumped storage system?

Back 41

Electricity cannot be stored in large quantities so when there is a sudden surge in demand a pumped storage station is used. This is a special type of hydroelectric power only used for changes in demand. At peak times it starts generating very quickly and at times of low demand it can be used to store energy for later use, by using electricity to pump water back uphill.

Front 42

What is the National Grid, and explain how it works?

Back 42

The electricity generated at power stations need to be distributed to homes and business all around the country. In the UK we have a National Grid. This is a huge network of underground cables and overhead power lines linking houses to power stations, which are sometime hundreds of miles long.

Front 43

What are the advantages of underground cables?

Back 43

• The cables are not an eyesore, unlike large pylons. They can be used in areas of outstanding natural beauty.
• The cables are protected from sever weather.

Front 44

What are the disadvantages of underground cables?

Back 44

• Its much more expensive to bury the cables.
• The cables have to be insulated and waterproofed; this means the cables get warmer, wasting more energy.
• It is very costly and disruptive to repair or renew damaged cables.
• The voltage used cannot be as high as in pylons, so more energy is wasted as heat.

Front 45

How were fossil fuels formed?

Back 45

Fossil fuels include, coal, oil and natural gas. They were all formed from remains of living plants or animals that died millions of years ago. They are a non-renewable energy resource that will be eventually used up.

Front 46

What are the disadvantages of using fossil fuels?

Back 46

• Burning fossil fuels releases carbon dioxide into the atmosphere. This increases global warming and leads to climate change.
• The fuels have to be mined/extracted and then transported. This damages wildlife habitats and there is an added risk of spills or leaks.
• The power stations and the mines/rigs are often very noisy.

Front 47

What is carbon capture?

Back 47

Carbon capture is a rapidly evolving technology, which in the future may dramatically reduce the amount of carbon dioxide that enters the atmosphere from the burning of fossil fuels.

Instead of travelling into the air, the carbon dioxide is trapped and stored underground. One day this may reduce the carbon dioxide released by a typical plant by as much as 80%

Front 48

What is nuclear fission?

Back 48

Splitting a nucleus into two smaller nuclei, releasing energy.

Electricity may be generated from nuclear reactors. Inside this reactor the nuclear fuel undergoes a nuclear reaction called nuclear fission. This reaction releases heat.

Front 49

What are 2 advantages of using nuclear power?

Back 49

• Huge amounts of electricity can be generated per kilogram of fuel.
• The fuel is not burnt, so there is no carbon dioxide released. Nuclear power does not contribute to global warming.
• The fuel is relatively cheap and easily available.

Front 50

What are 3 disadvantages of nuclear power?

Back 50

• Nuclear reactors produce highly radioactive waste. This is very dangerous and harmful. It needs to be stored carefully.
• There is the risk of a nuclear accident releasing radioactive waste into the environment.
• Nuclear reactors have a very slow start-up time. They can't react to sudden change in demand.
• The power stations contributes to both noise and visual pollution.

Front 51

What are renewable energy sources?

Back 51

Renewable energy sources are sources of energy that will never run out. Most turn turbines to generate the electricity.

Front 52

Name 5 renewable energy sources.

Back 52

• Wind
• Wave
• Tidal
• Hydroelectric
• Solar cells
• Geothermal
• Biomass

Front 53

Name the two types of waves that are around us everyday.

Back 53

There are two types of waves that are around us everyday. These are:

• transverse
• longitudinal

Front 54

What are waves a series of?

Back 54

Waves are a series of vibrations or oscillations. There are many different types of waves but all transfer energy from one place to another.

Front 55

What are transverse waves?

Back 55

In transverse waves to oscillations are at right angles to the directions of energy transfer. Transverse waves look like ripples on water. They are made up of peaks and troughs.

Front 56

What are longitudinal waves?

Back 56

In longitudinal waves the oscillations are parallel to the direction of energy transfer. A longitudinal wave is made up of compressions and rarefactions.

Compressions - Where the particles are bunched up, close together.

Rarefactions - Where the particles are further apart.

Front 57

Name 3 properties of waves

Back 57

Amplitude - in metres, m - maximum height of the wave, measured from the middle of the wave.

Wavelength - in metres, m - the distance from one peak to the next.

Frequency - in hertz, Hz - the number of peaks passing a point per second.

Front 58

What is reflection?

Back 58

When waves bounce off a surface are said to be reflected. All waves can be reflected.

The law of reflection states:

The angle of incidence = the angle of reflection

Front 59

What is refraction?

Back 59

When waves travel from one medium to another they can be refracted. If the speed of the wave changes, the wave changes direction. This is called refraction.

Front 60

What is diffraction?

Back 60

When waves pass through a gap or around an obstacle they spread out. This is called diffraction.

Front 61

What are electromagnetic waves?

Back 61

Electromagnetic waves are a special kind of transverse wave. Unlike other waves they don't need particles; they can travel through vacuum like space.

Front 62

What is the electromagnetic spectrum?

(Definition, not the types of electromagnetic waves)

Back 62

There are seven different electromagnetic waves that together form the electromagnetic spectrum. They can all travel through vacuum but they have different frequencies and wavelengths.

Front 63

Name the seven types electromagnetic waves

Back 63

In order of increasing energy and frequency:

• Radio waves
• Microwaves
• Infrared radiation
• Visible light
• Ultraviolet
• X-rays
• Gamma rays

In backwards order would show the increasing wavelength.

Front 64

What are two example of electromagnetic waves used for communication?

Back 64

As electromagnetic waves travel so fast they are very useful for communication. There are some example listed below.

• Radio waves - TV, radios, and wireless communication
• Microwaves - mobile phones and satellite TV
• Infrared - remote controls and some cable internet connections.
• Visible light - photography and some cable internet connections.

Front 65

What is the wave equation?

Back 65

The speed of a wave, its frequency, and its wavelength are all linked together in the wave equation:

Wave speed = frequency x wavelength

Front 66

What is the law of reflection?

Back 66

The law of reflection states that:

The angle of incidence = the angle of reflection

Front 67

What are sound waves and how are they produced?

Back 67

Sound waves are produced whenever an object vibrates. These vibrations cause neighbouring air particles to vibrate and the sound travels through the air.

Sound waves are longitudinal waves. The oscillations are parallel to the direction of energy transfer.

Like all waves, sound waves can be reflected, refracted, and diffracted. A reflection of a sound wave is called an echo.

Front 68

What is volume and how does it work?

Back 68

A louder sound (one with a higher volume) is created when the particles vibrate further. This gives the sound wave a larger amplitude.

The longer the amplitude, the louder the sound.

Front 69

What is an oscilloscope and what does it show?

Back 69

An oscilloscope can be used to produce picture of sound waves. Higher-pitched, louder sounds have a higher frequency (the waves are closer together) and a greater amplitude (they are taller).

Front 70

What are two sources of waves?

Back 70

Any object that emits a wave can be described as a wave source.

• Sound - speaker, police siren, car engine
• Light - lightbulb, galaxy
• Microwaves - satellites, microwave oven.

Front 71

What is the Doppler effect?

And explain how it works.

Back 71

When a wave source moves this affects the frequency and wavelength of the wave detected by stationary observers. This is called the Doppler effect.

• When the wave source moves away from the observer, the wave gets stretched out. The wavelength increases and the frequency decreases.
• When the wave source moves towards the observer the waves get all bunched up. the wavelength decreases and the frequency increases.

This effect can be heard when race cars or police sirens move past an observer.

Front 72

What is the Big Bang theory and what does it state?

Back 72

The Big Bang theory is the current scientific description for the origin of the Universe. It states:

• The Universe began around around 14 billion years ago.
• The Universe started from a very small, incredibly hot initial point.
• The Universe then exploded outwards and has been expanding ever since.

Front 73

What evidence is there for the Big Bang theory?

Back 73

There are two key pieces of evidence in support of this theory.

• The Universe is expanding: rewind time and the galaxies all get closer together as the Universe got smaller and smaller until its initial creation.
• Cosmic microwave background radiation: scientists are able to detect the heat left over from the Big Bang.

Front 74

What is red-shift and what does it show?

Back 74

The increase in wavelength of light emitted from an object that is moving away from the observer.

When galaxies move away from us the light they emit is stretched: its wavelength increases. As red is the longest wavelength of all the colours this effect is called red-shift.

When you look at the light from distant galaxies there are two key observations:

• Most galaxies show red-shift - they are moving away from us.
• The further a galaxy is away, the greater the red-shift - the faster the it is moving.

Front 75

What is cosmic microwave background radiation?

Back 75

The second key piece of evidence is cosmic microwave background radiation (CMBR).

CMBR is a form of radiation that fills the entire Universe; it is the same everywhere you look. It is the heat left over from the Big Bang. As the Universe expanded, it cooled. This initial heat is now in the microwave part of the electromagnetic spectrum.

The Big Bang theory is currently the only theory that can explain the existence of CMBR.