P5.1 & 5.2 Wave Behaviour & EM Spectrum

Question 1

What is the formula for wave velocity?

Answer 1

Wave Velocity === Frequency(Hz) xxx Wavelength(m)

Rearrange formula to work out other factors.

Question 2

What is the equation of motion?

Answer 2

v^2 — u^2 === 2as

v = Final Velocity(m/s)
u = Initial Velocity(m/s)
a = Acceleration(m/s^2)
s = Displacement(m)

Question 3

What is the electromagnetic spectrum?

Answer 3

The spectrum complete with different bands of frequencies that we call waves. Our eyes can only see one band of these called visible light.

Question 4

What are the waves on the electromagnetic spectrum and what order of frequency are they in?

Answer 4

Radio Waves, Microwaves, Infrared, Visible Light, Ultra Violet, X-Rays, Gamma Rays

Question 5

What are electromagnetic waves?

Answer 5

Electromagnetic waves consist of oscillating electric and magnet fields. They are transverse vibrating at 90 degrees from the direction. All electromagnetic waves can travel through vacuums at the speed of light. 3*10^8.

Question 6

How do you calculate wavelength?

Answer 6

Convert to standardised, common units.

Wave Velocity /// Frequency === Wavelength

Question 7

What are the oscillations of longitudinal waves?

Answer 7

The direction of longitudinal waves oscillations are parallel to direction of energy transfer. Compressions are where the particles in the medium are closest. Rarefractions are where the particles are furthest apart.

Question 8

What are the oscillations of transverse waves?

Answer 8

In transverse waves, the direction of the oscillations are at a right angle to the direction the wave and energy is travelling. The highest point of the wave is the crest and the lowest is the trough.

Question 9

What is wavelength, frequency, amplitude, and time period?

Answer 9

Wavelength is the distance from one point on the wave to the same point on the next wave.
Frequency is the amount of waves passing a point in a second. Measured in ‘Hz’.
Amplitude is the distance from the middle of the wave to the crest/trough in transverse or the distance of particles in compression in longitudinal. Measured in ‘m’.
Time Period is the time it takes a single wave to pass a point. Measured in ‘s’.

Question 10

What is a wave?

Answer 10

An oscillation that transfers energy

Question 11

How are EM waves used for communication?

Answer 11

Microwaves and radio waves communicate information
Infrared pulses used in remote controls
Visible light used in ships

Question 12

What are other uses of EM waves?

Answer 12

Microwaves and IR cook food
Visible light is used in optical storage
UV provides vitamin D
UV, X-rays and Gamma kill bacterial and cancerous cells

Question 13

Which waves are dangerous?

Answer 13

UV
X-rays
Gamma

Question 14

How is UV dangerous?

Answer 14

UV can damage the DNA in the cells of your skin. The cells then grow rapidly causing skin cancer.
Exposure can cause cataracts making the cornea cloudy

Question 15

How are X-rays dangerous?

Answer 15

X-rays can damage cells and cause cancers. This is why a radiographer stands behind a lead screen or in another room

Question 16

How are gamma rays dangerous?

Answer 16

Gamma rays can also damage or kill cells in your body

Question 17

How are infrared waves used for medical imaging?

Answer 17

A thermal imaging camera produces an image called a thermogram that shows regions of different temperatures

Question 18

How are x-rays used for imaging?

Answer 18

Bones absorb X-rays but soft tissues such as skin and muscle do not. The film used for X-rays darkens when absorbing X-rays and so shows details within a person