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 — the only form of heat transfer that works through a vacuum.

The sun warms you even through the vacuum of space — 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 0.5 m2 radiates power. Find it. (σ=5.67×10−8)

Example 4

challenge
The Sun's surface temperature is ≈5800 K. Using Wien's law (b=2.90×10−3 m⋅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=3 m2) is at 400 K. Find its radiated power. (σ=5.67×10−8)

Example 7

hard
Compare radiated power of a person (T=310 K, ε=0.97, A=1.7 m2) to surroundings at 293 K. (σ=5.67×10−8)

Example 8

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

Example 9

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

Example 10

medium
A black body has area 2 m2 at 300 K. Find its radiated power. (σ=5.67×10−8 W/(m2K4))

Example 11

medium
A black body has area 1.0 m2 at 400 K. Find its radiated power. (σ=5.67×10−8 W/(m2K4))

Example 12

medium
A grey body has emissivity ε=0.6, area 2.0 m2, at 500 K. Find the radiated power. (σ=5.67×10−8)

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=3000 K and radius R. Star B has TB=6000 K and radius R/2. Compare their luminosities.

Example 15

medium
A surface at 300 K radiates P1. The same surface at 600 K radiates P2. Find P2/P1.

Example 16

medium
A black body at 250 K radiates P0. Find its power at 1000 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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