FUNPHYS 3 - e-m radiation - Use in therapy and diagnosis

Question 1

What is e-m radiation?

Answer 1

E-M radiation is the complex interaction between changing Electric and Magnetic fields associated with the movement of charged particles.

Question 2

What does an electromagnetic spectrum show?

Answer 2

An electromagnetic spectrum shows the different types of e-m radiation that exist.

Question 3

List the order of the different types of waves in terms of increasing frequency and decreasing wavelength.

Answer 3

1. TV & AM/FM Radio waves: 10³ Hz
2. Microwaves: 10⁹ Hz
3. Infrared Waves (Body heat): 10¹¹ Hz
4. Visible Light (Red->violet): 10¹⁵ Hz
5. Ultraviolet: 10¹⁵ Hz
6. X-rays: 10¹⁷ Hz
7. Gamma Rays: 10¹⁹ Hz

Question 4

What speed do the different types of em radiation travel at?

Answer 4

All em waves travel at the same speed. They travel at the speed of light: 3 x 10⁸ m/s.

Question 5

What is the wave speed equation?

Answer 5

V_wave = wavelength x frequency

Question 6

What does em radiation consist of?

Answer 6

Photons

Question 7

What is the relationship between the energy of a photon and frequency?

Answer 7

The higher the frequency of a wave, the higher it’ss energy. This is why gamma rays have more energy than radio waves.

Question 8

What effect do em waves that have a frequency above 1 x 10¹⁵ Hz have on electrons? On body tissue?

Answer 8

Em waves above 1 x 10¹⁵ Hz can break bonds and ionize electrons of an atom, so they can cause DNA damage to the body. Em waves below 1 x 10¹⁵ Hz are non-ionizing and just emit heat.