Waves

Question 1

Wavelength, λ

Answer 1

Distance from a point on a wave to an identical point on the next wave. Measured in metres (m)

Question 2

Amplitude

Answer 2

Size of maximum disturbance from the centre line

Question 3

Period, T

Answer 3

Time taken for one full wave to pass a point Measured in seconds (s)

Question 4

Wave speed, v

Answer 4

Distance travelled by a wavelength in one second Measure in metres per second (m s-1)

Question 5

Wave Speed, v - formula

Answer 5

wavespeed = distance travelled/time

or

wavespeed = wavelength/period

Question 6

Frequency, f

Answer 6

Number of waves passing a fixed point every second Measured in hertz (Hz)

Question 7

Frequency, f - formula

Answer 7

frequency = number of waves/time

or

frequency = 1/period

Question 8

The Wave Equation

Answer 8

The wave equation links the speed, frequency and wavelength of a wave in one equation.

speed = frequency x wavelenth
v = fλ

or

speed = distance/time
v = d/t

Question 9

Types of Waves

Answer 9

Transverse waves -
With transverse waves, the motion of the particles (or medium) is at right angles to the direction of motion of the wave.
Examples of transverse waves include water waves and electromagnetic waves

Longitudinal waves -
With longitudinal waves, the motion of the particles (or medium) is in the same direction as the direction of motion of the wave. Examples of longitudinal waves include sound waves and shock waves

Question 10

Speed of Sound in Air

Answer 10

Under normal conditions, the speed of sound in air is measured as 340 m s-1. That means it can travel over 1km in 3 seconds. We can use this to predict the distance of a lightning strike. For ever 3 seconds between the “flash” and the “crash”, the sound has had to travel over 1 km.

Question 11

Comparing Sound Waves

Answer 11

Waves of different amplitude and frequency will sound different. When displayed on an oscilloscope they will also look different

Quiet Sound - Low Amplitude
Loud Sound - High Amplitude

Low Pitch - Low Frequency
High Pitch - High Frequency

Question 12

The Electromagnetic Spectrum

Answer 12

The electromagnetic spectrum is a family of electromagnetic waves which all travel at the speed of light, 3x108 ms-1.
All EM waves are transverse waves. Except for their speed, each part of the spectrum demonstrates different properties and therefore different applicationsas well as potential hazards.

Question 13

Order of Waves

Answer 13

Gamma Rays (high frequency, high energy, low wavelength)
X-Rays
Ultraviolet Light
Visible Spectrum
Infrared
Microwave
Radiowaves (low frequency, low energy, high wavelength)

Question 14

Gamma Rays - Uses

Answer 14

Treatment of cancers, through radiotherapy. Tracers, as rays are very penetrative but less ionizing than alpha or beta radiation (see Nuclear Physics in S4). Sterilisation of medical equipment

Question 15

X-Rays - Uses

Answer 15

Non-invasive/surgical method to locate/identify broken bones and other abnormalities within the body.

Question 16

Ultraviolet - Uses

Answer 16

Used in the treatment of skin problems and sterilization of equipment.

Question 17

Visible - Uses

Answer 17

Medical applications include lasers. Knowledge of light allows the development of glasses, endoscopes and optical fibres

Question 18

Infrared - Uses

Answer 18

This is radiated heat. Used in physiotherapy and can be detected and displayed as thermograms, identifying injuries or heat loss in homes.

Question 19

Microwaves - Uses

Answer 19

Used in communications as well as the heating of foods

Question 20

Radiowaves - Uses

Answer 20

Mainly used in communications and radar

Question 21

Refraction of Light

Answer 21

refraction occurs when light passes from one transparent medium to another. when this happens, the light will experience a change in speed and wavelength but not frequency. this is known as refraction. there may also be a change in direction of the light when at an angle from the normal

when light passes into a fender medium the angle of refraction (r) is less than the angle of incidence (i). all angles are measured from the normal line

Question 22

diffraction

Answer 22

all types of waves are able to diffract if they have large enough wavelengths. due to their long wavelength (low frequency) radio waves are able to diffract round large object such as mountains.