Electromagnetic Spectrum
Notes
Electromagnetic spectrum consists of seven kinds of waves
radio waves
microwaves
infra-red radiation
visible light
ultraviolet radiation
X-rays
gamma rays
The shorter the wavelength, the higher the frequency.
Properties of electromagnetic waves
They are all transverse waves.
They transfer energy from one place to another.
They all show wave properties such as reflection and refraction.
They can all travel through a vacuum
They all travel at a speed of 3 x 108 ms-1 in a vacuum.
The equation [wave speed = frequency x wavelength] applies to them.
Uses of electromagnetic waves
Effects of electromagnetic waves on cells and tissue
High energy electromagnetic waves (those with higher frequencies) can ionize atoms and molecules of living matter, causing damage to body cells.
MCQ
1. Which of the following make(s) use of ultraviolet radiation?
(1) scanning to see an image of a developing baby inside the womb
(2) treating cancer
(3) sterilisation
a. (3) only
b. (1) and (2) only
c. (1) and (3) only
d. (2) and (3) only
2. Which of the following electromagnetic waves will cause heating?
(1) radio waves
(2) infrared radiation
(3) X-rays
a. (2) only
b. (1) and (2) only
c. (2) and (3) only
d. (1), (2) and (3)
3. Which of the following statements about electromagnetic waves is/are true?
(1) radio waves have the shortest wavelengths in the electromagnetic spectrum
(2) gamma rays have the highest frequencies in the electromagnetic spectrum
(3) infrared radiation has a longer wavelength than ultraviolet radiation
a. (1) and (2) only
b. (1) and (3) only
c. (2) and (3) only
d. (1), (2) and (3)
4. Which of the following statements about electromagnetic waves is/are true?
(1) electromagnetic waves travel at the same speed in any medium
(2) all electromagnetic waves can ionise living cells
(3) all electromagnetic waves are transverse waves
a. (3) only
b. (1) and (3) only
c. (2) and (3) only
d. (1), (2) and (3)
MCQ Answers
1.a
2. d
3. c
4. a