chapter 2

Question 1

describe the rod test to test thermal conductivity

Answer 1

The rods need to be the same width and length for it to be a fair test. Each rod is coated with a thin layer of wax near one end, the uncoated ends are then heated together. The wax then melts fastest on the one with that best conducts energy.

Question 2

what conducts energy better. Metals or non metals

Answer 2

metals

Question 3

what is a batter conductor copper or steel

Answer 3

copper

Question 4

what is a better conductor , glass or wood

Answer 4

glass

Question 5

what does a greater thermal conductivity mean

Answer 5

the more energy per second it transfers by conduction

Question 6

what type of thermal conductivity do insulators need to have and why

Answer 6

a low thermal conductivity, so the energy transfer through them is as low as possible

Question 7

what does the energy transfer per second through a layer of insulating material depend on

Answer 7

temperature difference across the material, thickness, thermal conductivity of the material

Question 8

what 2 ways reduce energy transfer as much as possible

Answer 8

the thermal conductivity being as low as possible, the material should be as thick as it can be

Question 9

what type of radiation comes from the sun

Answer 9

infrared radiation

Question 10

what happens to the wavelength of visible light spectrum as you go from blue to red light

Answer 10

it increases

Question 11

which has a longer wavelength infrared or visible light

Answer 11

infrared

Question 12

what does a higher temperature of an object mean

Answer 12

the more infrared radiation it gives out in a given time

Question 13

what is a body

Answer 13

object

Question 14

how does a body have an constant temperature

Answer 14

when it emits infrared radiation at the same rate it absorbs it

Question 15

what is a perfect black body

Answer 15

an object that absorbs all the radiation that hits it , it doesn’t reflect any radiation and doesn’t transmit any (no radiation passes through it )

Question 16

what is a good absorber also

Answer 16

a good emitter

Question 17

what else is a perfect black body, other than absorbing all infrared radiation

Answer 17

a good emitter

Question 18

what is the radiation emitted by a black body called

Answer 18

black body radiation

Question 19

what is the relationship between an object having a constant temperature and the wavelength’s it emits

Answer 19

it emits radiation across a continuous range of wavelengths

Question 20

what happens to the intensity of wavelengths an object emits if its temperature is increased

Answer 20

the intensity of the radiation it emits is greater at every wavelength

Question 21

what happens to the increase in intensity of radiation emitted when there is a shorter wavelength of radiation

Answer 21

there is a greater increase in intensity at that wavelength

Question 22

how does an objects temperature increase

Answer 22

when it absorbs radiation faster than it emits it

Question 23

why do rescue teams use light coloured shiny blankets (foil) to keep people warm

Answer 23

a light shiny surface emits less radiation then a dark matt surface- this keeps the person warm

Question 24

What factors affect the Earth’s temperature in relation to radiation from the Sun?

Answer 24

How much light and infrared radiation from the Sun is reflected back into space or absorbed by the Earth’s atmosphere or surface.
How much radiation is emitted from the Earth’s surface and atmosphere into space.

Question 25

what would happen to the temperature if the earth had no atmosphere and why

Answer 25

it would go really cold - particles in the atmosphere re-emit infrared radiation back into the ground, without the atmosphere the surface would emit radiation back into space

Question 26

what gasses absorb longer wavelength radiation and prevent it escaping into space, and what is this effect

Answer 26

water vapour, methane and carbon dioxide. The process makes the earth warmer than it would be if these gases weren't in the atmosphere, as they emit radiation into the earths surface

Question 27

what does an experiment on a substances temperature rise depend on

Answer 27

that amount of energy supplied, mass of substance, what the substance is

Question 28

what is specific heat capacity

Answer 28

the energy needed to raise the temperature of 1kg of the substance by 1 degree Celsius

Question 29

what is equation for energy transferred

Answer 29

energy transferred=mass x specific heat capacity x temperature change

Question 30

what are ways you can reduce the rate of energy transfer at home

Answer 30

loft insulation, thicker bricks with lower thermal conductivity, double glazed windows, aluminum foil between a radiator panel and the wall

Question 31

what is a loft insulation material and why is it good

Answer 31

fiberglass - It is a good insulator as the air between the fibers reduces the rate of energy transfer through conduction. The thicker the insulation the lower the rate of energy transfer is

Question 32

how does cavity wall insulation work

Answer 32

it traps air in small pockets, reducing the rate of energy transfer by conduction

Question 33

how do double glazed windows work

Answer 33

they are 2 layers of glass with dry air or a vacuum between the layers. The thicker the glass the lower the rate of energy transfer by conduction will be

Question 34

how do thicker bricks help

Answer 34

they lower the rate of energy transfer from in the building

Question 35

what do solar panels do

Answer 35

absorb infrared radiation from the sun to generate electricity (solar cell panels) or to heat water ( solar heating panels)