Question 21
Question 21 of 40
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No letter options?
Older MCQs might not have the typical A, B, C, D choices. They have choices 1, 2, 3, and a combination of them is the answer. Below is the key that maps such combinations to the answer.
A 1, 2 and 3 are correct
B 1 and 2 only are correct
C 2 and 3 only are correct
D 1 only is correct
Topics Tested
2. Thermal physics
2.3.3. Radiation

Describe the process of thermal energy transfer by infrared radiation and know that it does not require a medium

3. Waves
3.4. Sound

Explain why sound waves cannot travel in a vacuum and describe an experiment to demonstrate this

3. Waves
3.3. Electromagnetic spectrum

Know that the speed of all electromagnetic waves in: (a) a vacuum is 3.0 × 10⁸ m/s (b) air is approximately the same as in a vacuum