absorption and emission of infrared radiation:

Question 1

the hotter the body

Answer 1

-the more infrared radiation it gives out in a given time

-the greater the proportion of emitted radiation is visible light

Question 2

Factors affecting temperature

Answer 2

-if rate absorption is Greater than the rate of emission the Temperature of the body is Increasing

-if rate absorption is the equal to the rate of emission the Temperature of the body is constant

-if rate absorption is the less than the rate of emission the Temperature of the body is decreasing

Question 3

Factors affecting the Earth’s temperature

Answer 3

-concentration of greenhouse gases such as water vapour, methane and carbon dioxide.

-Earth’s temperature also depends on rates at which light radiation and infrared radiation are:

-absorbed by the Earth’s surface and atmosphere

-emitted by the Earth’s surface and atmosphere

Question 4

what happens when visible light and high frequency infrared radiation are absorbed by the surface of the Earth,

Answer 4

• the planet’s internal energy increases and the surface gets hotter.

-Some of this energy is transferred to the atmosphere by
conduction
and
convection
.

Question 5

what is the The greenhouse effect

Answer 5

-The ‘greenhouse effect’ caused by naturally occurring greenhouse gases,

• stabilises the surface temperature of Earth. This allows the planet to support life.

Question 6

rq practical- investigating infrared radiation

Answer 6

1)Place a Leslie cube on a heat-resistant mat. Almost fill it with boiling water and replace the lid.

2)Leave for one minute. This is to enable the surfaces to heat up to the temperature of the water.

3)Use infrared detector to measure intensity of infrared radiation emitted from each surface, or the temp of the surface. Make sure that detector is same distance from each surface for each reading.

Results
Record results in a suitable table. The example below also shows some example results.

Plot a bar chart to show the results.
Use your results to order the different surfaces from the best emitter to the worst emitter of infrared radiation.

Question 7

hazards and control measures

Answer 7

hazard: Boiling water

consequence :scalds

control measures : Pour water slowly, using a funnel if necessary. Do not move the Leslie cube until it has cooled.

Question 8

Aim of the experiment

Answer 8

To investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface.