Practice Radiation (Heat Transfer) in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

Heat transfer through electromagnetic waves that require no medium โ€” the only form of heat transfer that works through a vacuum.

The sun warms you even through the vacuum of space โ€” that's radiation.

Showing a random 20 of 50 problems.

Example 1

challenge
A black body radiates 1000 W at 300 K. Find its radiated power if heated to 450 K (same area).

Example 2

easy
Does radiation require a medium such as air or water to transfer energy?

Example 3

medium
A black body at 500 K with area 0.5ย m20.5 \text{ m}^2 radiates power. Find it. (ฯƒ=5.67ร—10โˆ’8\sigma = 5.67\times10^{-8})

Example 4

challenge
The Sun's surface temperature is โ‰ˆ5800โ€‰K\approx 5800\,\text{K}. Using Wien's law (b=2.90ร—10โˆ’3โ€‰mโ‹…Kb = 2.90\times10^{-3}\,\text{m}\cdot\text{K}), find the peak emission wavelength.

Example 5

easy
Is thermal infrared radiation from a warm cup of tea the same kind of radiation as gamma rays from a radioactive sample?

Example 6

medium
A black body (A=3ย m2A = 3 \text{ m}^2) is at 400 K. Find its radiated power. (ฯƒ=5.67ร—10โˆ’8\sigma = 5.67\times10^{-8})

Example 7

hard
Compare radiated power of a person (T=310โ€‰KT = 310\,\text{K}, ฮต=0.97\varepsilon = 0.97, A=1.7โ€‰m2A = 1.7\,\text{m}^2) to surroundings at 293โ€‰K293\,\text{K}. (ฯƒ=5.67ร—10โˆ’8\sigma = 5.67\times10^{-8})

Example 8

medium
What does the Stefan-Boltzmann constant have units of?

Example 9

medium
Convert 127ยฐC to kelvin, then state the factor by which radiated power exceeds that at 200 K.

Example 10

medium
A black body has area 2ย m22 \text{ m}^2 at 300 K. Find its radiated power. (ฯƒ=5.67ร—10โˆ’8ย W/(m2K4)\sigma = 5.67 \times 10^{-8} \text{ W/(m}^2\text{K}^4))

Example 11

medium
A black body has area 1.0โ€‰m21.0\,\text{m}^2 at 400โ€‰K400\,\text{K}. Find its radiated power. (ฯƒ=5.67ร—10โˆ’8โ€‰W/(m2K4)\sigma = 5.67\times10^{-8}\,\text{W/(m}^2\text{K}^4))

Example 12

medium
A grey body has emissivity ฮต=0.6\varepsilon = 0.6, area 2.0โ€‰m22.0\,\text{m}^2, at 500โ€‰K500\,\text{K}. Find the radiated power. (ฯƒ=5.67ร—10โˆ’8\sigma = 5.67\times10^{-8})

Example 13

medium
A radiating body at 250 K is heated to 500 K. By what factor does its radiated power increase?

Example 14

medium
Star A has temperature TA=3000โ€‰KT_A = 3000\,\text{K} and radius RR. Star B has TB=6000โ€‰KT_B = 6000\,\text{K} and radius R/2R/2. Compare their luminosities.

Example 15

medium
A surface at 300โ€‰K300\,\text{K} radiates P1P_1. The same surface at 600โ€‰K600\,\text{K} radiates P2P_2. Find P2/P1P_2/P_1.

Example 16

medium
A black body at 250โ€‰K250\,\text{K} radiates P0P_0. Find its power at 1000โ€‰K1000\,\text{K}.

Example 17

medium
Why does Wien's displacement law say hotter objects glow with a shorter peak wavelength?

Example 18

medium
Why does a cup of tea cool faster in a cold room than in a warm room, considering radiation?

Example 19

easy
Which heat-transfer mode warms you from the Sun across the vacuum of space?

Example 20

easy
Why does a matte-black surface radiate heat more efficiently than a polished silver surface at the same temperature?
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