Science A (Core): Physics - The Basics

Question 1

How is heat energy (infrared radiation) given out by objects?

Answer 1

All objects emit and absorb heat (hot objects emit more than they absorb and cold objects absorb more than they emit)

Question 2

What colours absorb and emit more heat than others?

Answer 2

Dark, matt colours are good absorbers and emitters

Light, shiny colours are bad absorbers and emitters

Question 3

What are the 3 states of matter and how are the particles arranged?

Answer 3

Solids: particles close together and fixed

Liquids: particles quite close but can move around

Gases: particles spread apart and move freely around

Question 4

What is conduction and where does it occur best in?

Answer 4

Conduction is the transfer of energy by particles vibrating (mainly in solids and especially in metals)

Question 5

What is convection and where does it occur best in?

Answer 5

Convection is the transfer of energy by particles moving around (in gases and liquids)

Question 6

What is the difference between evaporation and condensation?

Answer 6

Evaporation is when a liquid changes into a gas

Condensation is when a gas changes into a liquid

Question 7

What can affect the rate of heat transfer?

Answer 7

Heat transfer is affected by: surface area; material type (conductor / insulator); the temperature difference (a big temperature difference means a faster energy transfer)

Question 8

How can heat transfer be reduced?

Answer 8

Conduction, convection and radiation can all be reduced

Question 9

How is heat loss reduced in the home?

Answer 9

Insulation (cavity wall; loft; double glazing etc…)

Question 10

What is a U-value?

Answer 10

A U-value is a measure of how well heat can pass through a material

High U-value = lots of heat loss

Question 11

How can insulation save you money?

Answer 11

Payback time = initial cost ÷ annual saving

Payback time is the time it takes to save the amount of money spent on the insulation

Question 12

What is specific heat capacity?

Answer 12

How much energy something can store (the amount of energy needed to raise 1kg of material by 1^oC)

Question 13

How can you calculate how much energy is stored in a material?

Answer 13

E = m x c x Ѳ

Energy (J) = Mass (kg) x specific heat capacity (J/kg^oC) x temperature change (^oC)

Question 14

What is the rule with energy?

Answer 14

Energy cannot be created or destroyed, only transferred

Electrical > light + sound

Chemical > kinetic > gravitational

Question 15

What is efficiency?

Answer 15

All machines waste energy (usually as heat)

Efficiency is how much energy is transferred usefully

Efficiency = useful energy out ÷ total energy in

Question 16

What is a sankey diagram and what does it show?

Answer 16

A sankey diagram shows how much energy of the input is changed into different types of energy – the wider the arrow the more energy it shows

Question 17

How can you work out how much electrical energy is transferred by an appliance

Answer 17

E = P x t

Energy transferred = power of the appliance x time it is used for

Question 18

What is electricity measured in?

Answer 18

Kilowatt-hours

(kWh)

Question 19

How is the cost of electricity calculated?

Answer 19

Cost = energy transferred (kWh) x price per kWh

This is often shown on an electricity meter

Question 20

How is electricity transferred across the UK?

Answer 20

The National Grid

Question 21

What is a non-renewable energy resource?

Answer 21

An energy resource that will run out one day (e.g. coal, oil, gas and nuclear fuel)

Question 22

How are energy sources used to generate electricity?

Answer 22

Fuel is burnt / reacted releasing heat which turns water to steam turning turbines and generators which generate the electricity

Question 23

How does the start-up time for power stations vary?

Answer 23

Gas – quickest

Oil

Coal

Nuclear – longest

Question 24

What is a renewable energy resource?

Answer 24

An energy resource which will never run out (wind, wave, tide, hydroelectric, solar, biofuel etc…)

Question 25

What are the benefits and disadvantages of non-renewables?

Answer 25

Fossil fuels are quick and reliable and relatively cheap however they release CO₂ as well as oil spills / mining is ugly and dangerous

Nuclear is very reliable but the waste is very dangerous

Question 26

What are the benefits and disadvantages of renewables?

Answer 26

Renewables will never run out and are generally clean and good for the environment, however they are not reliable (no wind then no turbine / no sun then no solar panel)

Question 27

What are the good and bad points for biofuels?

Answer 27

Biofuels are carbon neutral however trees still need to be deforested

Question 28

What is carbon capture and storage?

Answer 28

Carbon dioxide can be ‘caught’ and put into holes in the North Sea where oil and gas used to be (reducing global warming risks)

Question 29

What are the basic properties of a wave?

Answer 29

Amplitude = energy of wave

Wavelength = length of one full wave

Frequency = number of waves per second (Hz)

Question 30

What is the difference between a transverse and longitudinal wave?

Answer 30

A transverse wave has vibrations up and down the wave direction

A longitudinal wave has vibrations along the direction of the wave (with compressions and rarefactions)

Question 31

How can wave speed be calculated?

Answer 31

Wave speed = frequency x wavelength

V = f x λ

Question 32

What are the laws of reflection?

Answer 32

Angle of incidence = angle of reflection

Question 33

How does a mirror work?

Answer 33

A virtual image is shown in a mirror

Question 34

What is diffraction?

Answer 34

The spreading out of a wave

Question 35

What is refraction?

Answer 35

Waves changing direction (due to different mediums)

Question 36

What is the electromagnetic spectrum made of?

Answer 36

Gamma rays (high frequency)

X-rays

Ultraviolet

Visible light

Infrared

Microwaves

Radio waves (low frequency)

*High frequency = short wavelength

Question 37

What are the different electromagnetic waves used for?

Answer 37

Gamma – cleaning medical equipment

X-rays – medical imaging

Ultraviolet – bank notes authenticity

Visible light – optical fibres

Infrared – remote controls

Microwaves – food cooking / phones

Radio waves – television and radio

*Some waves such as gamma, x-rays and ultraviolet are bad for health

Question 38

How do we hear?

Answer 38

Sound waves travel and vibrate

Question 39

What is the pitch of a sound wave?

Answer 39

Higher frequency = higher pitch (a squeaking mouse versus a mooing cow)

Question 40

What is the Doppler effect and red-shift?

Answer 40

Wavelength and frequency change if the wave source moves

Galaxies are moving away from us and their light is red-shifted

Question 41

How did the universe begin?

Answer 41

Big bang – the universe is still expanding