Properties of Electromagnetic Waves Flashcards

All 6 cards in this deck

What type of wave is every electromagnetic wave?

Transverse.

What is the speed of electromagnetic waves in a vacuum?

$3 \times 10^8$ m/s — the same for every part of the EM spectrum.

What do all electromagnetic waves transfer, and between what?

Energy, from a source to an observer.
e.g. infrared from a fire transfers energy to your skin.

True or false? Electromagnetic waves need a medium to travel through.

False. They can travel through a vacuum, e.g. light from the Sun crossing space.

What are the steps to find the frequency of an electromagnetic wave from its wavelength?
e.g. an EM wave in a vacuum with wavelength $3$ m

1. Use $v = f\lambda$ with $v = 3 \times 10^8$ m/s
2. Rearrange: $f = v \div \lambda$
3. $f = 3 \times 10^8 \div 3 = 1 \times 10^8$ Hz

What are the steps to find how far an electromagnetic wave travels in a given time?
e.g. light from the Sun takes $500$ s to reach Earth

1. Use distance = speed × time, speed $= 3 \times 10^8$ m/s
2. Substitute: $3 \times 10^8 \times 500$
3. Distance $= 1.5 \times 10^{11}$ m