P2- Energy transfer by heating

Question 1

Thermal conductivity

Answer 1

The rate at which a material transfers thermal energy

Question 2

2 ways to reduce the rate of thermal energy transfer with insulators

Answer 2

Low thermal conductivity of the insulating material
Thick layer of insulating material

Question 3

Best conductors and insulators?

Answer 3

Conductors- metals
Insulators- non metals, wool, fibreglass

Question 4

Why do solids have a high thermal conductivity?

Answer 4

Particles are closer together, gain KE, collide more, transfer thermal energy

Question 5

What happens to the infrared radiation when the temperature of object increases?

Answer 5

Higher the temperature of the object, the more infrared radiation it emits

Question 6

Blackbody radiation

Answer 6

Radiation emitted by an object that absorbs all radiation incident on it

Question 7

When does the temperature of an object increase? (in terms of radiation)

Answer 7

If it absorbs more radiation than it emits

Question 8

2 factors that affect the temperature of the Earth (radiation)

Answer 8

-Absorption of infrared radiation from the Sun
-Emission of infrared radiation from Earth’s atmosphere

Question 9

Specific heat capacity

Answer 9

Energy required to raise the temperature of 1kg of a substance by 1oc

Question 10

If an object had high thermal conductivity what would its shc be?

Answer 10

High thermal conductivity=lower specific heat capacity

Question 11

The greater the object’s mass, the temperature increases…?

Answer 11

Slower

Question 12

How to investigate shc of a material?

Answer 12

-Measure mass of block
-Place immersion heater in block, connect ammeter and power pack in series, voltmeter in parallel
-Place thermometer in block w water, record initial temp
-Insulate block w foam
-Record ammeter and voltmeter reading
-Turn power pack on, wait 10 mins, record finial temp
-Calculate temp change
-Calculate power
-Calculate energy transferred
-Calculate shc

Question 13

4 ways to reduce energy transfer in home

Answer 13

Loft insulation, cavity wall insulation, double-glazed windows, foil behind radiator

Question 14

Loft insulation reducing energy transfer

Answer 14

-Uses fibreglass wool (good insulator)
-Air between fibres reduces conduction

Question 15

Cavity wall insulation reducing energy transfer

Answer 15

-Space between two layer of brick filled with insulator
-Traps air, reduces conduction

Question 16

Double-glazed windows reducing energy transfer

Answer 16

-Vacuum between two panes of glass
-Low conductivity of glass, reduces conduction
-Vacuum, reduces convection

Question 17

Foil behind radiator reducing energy transfer

Answer 17

-Reflects radiation away from wall, into room
-Less radiation

Question 18

3 ways thermal energy is transferred

Answer 18

Conduction, convection, radiation