Electromagnetic (EM) Waves Flashcards

All 8 cards in this deck

What are the three properties that all electromagnetic waves share?

They are transverse, they transfer energy from a source to an absorber, and they all travel at the same speed in a vacuum (or air).

List the seven groups of the electromagnetic spectrum in order from longest to shortest wavelength.

Radio, microwave, infrared, visible light, ultraviolet, X-rays, gamma rays.

What is the speed of all electromagnetic waves in a vacuum?

$3 \times 10^8$ m/s (the speed of light).

True or false? Gamma rays travel faster than radio waves in a vacuum.

False. All electromagnetic waves travel at the same speed, $3 \times 10^8$ m/s, in a vacuum.

Which colour of visible light has the longest wavelength, and which has the shortest?

Red has the longest wavelength; violet has the shortest.

What are the steps to convert a wavelength given in nanometres into metres in standard form?

e.g. 300 nm

1. Use $1$ nm $= 1 \times 10^{-9}$ m: $300 \times 10^{-9}$ m
2. Write in standard form: $3 \times 10^{-7}$ m

What are the steps to find the wavelength of an electromagnetic wave in air from its frequency?

e.g. a radio wave of frequency 100 MHz ($1 \times 10^8$ Hz)

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

True or false? The electromagnetic waves form a continuous spectrum.

True. The seven groups merge into one another, so there are no sharp gaps between them.