Waves

Question 1

Longitudinal waves

Answer 1

Where the particles vibrate parallel to the direction of the wave travel (and energy transfer). These waves show areas of compressions and rarefactions

Question 2

Transverse waves

Answer 2

Where the particles vibrate perpendicular to the direction of the wave travel (and energy transfer). These waves show areas of crests (peaks) and troughs

Question 3

Amplitude

Answer 3

Is its height, measured from the middle of the wave to its top (or from the middle to its bottom)

Question 4

Wavefront

Answer 4

A useful way of picturing waves from above: each wavefront is used to represent a single wave

Question 5

Frequency

Answer 5

Is the number of waves passing a point (or being created or received) every second - it is helpful to think of it as being the waves per second. Measured in Hertz

Question 6

Wavelength

Answer 6

Is the distance from a point on one wave to the same point on the next wave. Usually, this is measured from the top of one wave to the top of the next wave. Measured in metres (a distance)

Question 7

Period of a wave

Answer 7

The time it takes for two consecutive crests (one wavelength) to pass a specified point. The wave period is often referenced in seconds, e.g. one wave every 6 seconds

Question 8

What does a wave transfer?

Answer 8

They transfers energy from one place to another without transferring matter

Question 9

Wave speed equation

Answer 9

Wave speed = frequency × wavelength
v = f × λ

Question 10

Frequency equation

Answer 10

Frequency = 1/time period

Question 11

Use the relationships in different contexts in terms of sound waves and electromagnetic waves

Question 12

Doppler Effect

Answer 12

The apparent change in wavelength and frequency of a wave emitted by a moving source

Question 13

Explain why there is a change in the observed frequency and wavelength of a wave when its source is moving relative to an observer (Doppler Effect)

Answer 13

Ahead of the car wavefronts are compressed as the car is moving in the same direction as the wavefronts. This creates a shorter wavelength and a higher frequency. Behind the car, wavefronts are more spread out as the car is moving away from the previous wavefronts. This creates a longer wavelength and a lower frequency.

Question 14

Reflection

Answer 14

A wave hits a boundary between two media and does not pass through, but instead stays in the original medium

Question 15

Refraction

Answer 15

A wave passes a boundary between two different transparent media and undergoes a change in direction

Question 16

Why are all waves Reflected and Refracted?

Question 17

Order of Electromagnetic Spectrum

Answer 17

Radio, microwave, infrared, visible light, ultraviolet, x-ray, and gamma ray radiations (Roger, Might, Interestingly go on, Vacation, Using an, X-model while, Giggling)

Question 18

Order of Electromagnetic Spectrum (in terms of decreasing wavelength and increasing frequency)

Question 19

Radio wave uses and effects

Answer 19

Broadcasting and communications

Question 20

Microwave uses and effects

Answer 20

Cooking and satellite transmissions
Internal heating of body tissue

Question 21

Infrared uses and effects

Answer 21

Heaters and night vision equipment
Skin burns

Question 22

Visible light uses and effects

Answer 22

Optical fibres and photography

Question 23

Ultraviolet uses and effects

Answer 23

Fluorescent lamps
Damage to surface cells and blindness

Question 24

X-ray uses and effects

Answer 24

Observing the internal structure of objects and materials, including for medical applications

Question 25

Gamma rays uses and effects

Answer 25

Sterilising food and medical equipment cancer, mutation

Question 26

Law of Reflection

Answer 26

When a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection

Question 27

Investigate the refraction of light, using rectangular blocks, semi-circular blocks and triangular prism

Answer 27

• Set up your apparatus as shown in the diagram using a rectangular block
• Shine the light ray through the glass block
• Use crosses to mark the path of the ray.
• Join up crosses with a ruler
• Draw on a normal where the ray enters the glass block
• Measure the angle of incidence and the angle of refraction and add these to your results table
• Comment on how the speed of the light has changed as the light moves between the mediums
• Repeat this for different angles of incidence and different glass prisms.

Question 28

Relationship between refractive index, angle of incidence and angle of refraction equation

Answer 28

n = sin i/sin r

Answer 29

• Set up your apparatus as shown in the diagram using a rectangular block.
• Shine the light ray through the glass block
• Use crosses to mark the path of the ray.
• Join up crosses with a ruler
• Draw on a normal where the ray enters the glass block
  -Measure the angle of incidence and the angle of refraction and add these to your results table
• Calculate the refractive index
• Repeat steps 2 – 7 using a different angle of incidence
• Find an average of your
  results.

Question 30

Role of total internal reflection in transmitting information along optical fibre and prisms

Answer 30

To capture the light transmitted in optical fibre and confine the light to the core of the fibre

Question 31

Critical angle c

Answer 31

The angle of incidence to which the angle of refraction is equivalent to

Question 32

Relationship between critical angle and refractive index equation

Answer 32

sin c = 1/n