1a) Energy

Question 0

What does radiation depend on?

Answer 0

Surface colour - dark absorb and emit more, light reflects

Texture - Matt absorb and emit more, shiny reflect

Question 1

In what three ways can heat be transferred?

Answer 1

Radiation (infrared radiation)
Conduction (through solids)
Convection (through liquids and gases)

Question 2

Define conduction of heat energy

Answer 2

Process where vibrating particles pass on their extra kinetic energy to neighbouring particles

Question 3

Define convection of heat

Answer 3

More energetic particles move from the hotter region to a colder region and take their heat energy with them

Due to changes in density

Question 4

Why would the rate of evaporation be faster?

Answer 4

Temp is higher
Density is lower
Surface area is larger
Airflow over liquid is greater (so concentration of air is lower)

Question 5

Why would the rate of condensation be faster?

Answer 5

Temp of gas is lower
Temp of surface touching the gas is lower
Density is higher
Airflow is less (higher concentration of air)

Question 6

How to work out payback time of a method of insulation?

Answer 6

Payback time = initial cost/ annual saving

Question 7

What is specific heat capacity?

Answer 7

Amount of energy needed to raise the temperature of 1kg of a substance by 1oC

How much energy a substance can store

Question 8

What is the specific heat capacity of water?

Answer 8

4200J/KgoC

Question 9

What is the law of conservation of energy?

Answer 9

Energy can be transferred usefully from one form to another, stored or dissipated
But it can NEVER be created or destroyed

Question 10

Formula for efficiency of energy

Answer 10

Efficiency = useful energy out / total energy in

OR

Efficiency = useful power out / total power in

Question 11

Give an example of an exception to the rule that ‘no device is 100% efficient’

Answer 11

Electric heaters - 100% efficient

All electricity is ultimately usefully converted to heat energy

Question 12

What are the nine types of energy?

Answer 12

Heat/ Thermal, Electrical, Light, Chemical, Elastic Potential, Sound, Gravitational potential, Nuclear, Kinetic/movement

Question 13

What is kilowatt hour?

Answer 13

Units of electrical energy

Amount of electrical energy used by 1KW appliance left on for 1 hour

Question 14

How to work it the no.of units (kwh) used?

Answer 14

No. Of units used = power x time

kwh) (Kw) (Hours

Question 15

Work out the cost of electricity

Answer 15

Cost = no. of units x price per unit

Question 16

Disadvantages and advantages of battery radios and clockwork radios

Answer 16

Battery radios - expensive, need replacing, can run out, use harmful chemicals to make them
Clockwork - free, winding needed every few hours to recharge (inconvenient), good for the environment

Question 17

Describe the particle arrangement of each state

Answer 17

Solid - regular arrangement, fixed position, strong forces of attraction, hold particles close together
Liquids - weaker attraction forces, close together, can move past each other, irregular arrangements
Gases - almost no attraction forces, free to move about, spaced out

Question 18

Describe the particle energies of each state

Answer 18

Solid - not much energy, can only vibrate in fixed positions
Liquid - more energy than solid particles, move in random directions at low speeds
Gases - more energy than solid and liquid particles, free to move in random directions at high speeds

Question 19

Why is conduction more efficient through a short fat rod than a long thin one?

Answer 19

The electrons have a shorter path to travel through so heat is passed through quicker

Question 20

How do solar panels work?

Answer 20

Contain water pipes under a black surface
Radiation from sun absorbed by black surface to heat water in pipes
Water can be pumped to radiators to heat the building