National 5 Physics - Waves

What do all waves transfer?

Energy

What is the definition of a transverse wave?

A wave in which the oscillations are perpendicular to the direction of energy transfer.

What is the definition of a longitudinal wave?

A wave in which the oscillations are parallel to the direction of energy transfer.

What are two examples of transverse waves?

Water waves and waves on the electromagnetic spectrum

What is one example of a longitudinal wave?

Sound waves

What is a wave’s frequency?

The number of waves passing a point per second, measured in Hertz (Hz).

What is a wave’s period?

The time it takes for one complete wave cycle to pass a point, measured in seconds.

What is a wave’s wavelength?

The distance between two consecutive points on a wave, such as crest to crest or trough to trough, measured in meters.

What is a wave’s amplitude?

The distance from the resting point to a crest or trough, measured in metres.

What is the relationship between amplitude and energy produced?

The amplitude of a wave is directly proportional to the energy it carries; higher amplitudes correspond to greater energy levels.

What is the speed of light in air?

3 × 10⁸ ms^-1

What is the speed of sound in air?

340 ms^-1, depending on temperature and pressure.

What do all electromagnetic waves have in common?

They are all transverse waves and they all travel at the speed of light.

What is the order of the members of the electromagnetic spectrum, from lowest to highest frequency?

Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays

Which member of the electromagnetic spectrum has the longest wavelength/lowest frequency?

Radio waves

Which member of the electromagnetic spectrum has the shortest wavelength/highest frequency?

Gamma rays

What detects radio waves?

Aerials and receivers

What detects microwaves?

Aerials and receivers

What detects ultraviolet radiation?

Fluorescent materials and photographic film

What detects infrared radiation?

Photodiodes, thermistors, thermocouples, and infrared cameras

What detects visible light?

Photographic film and the retina of the eye

What detects ultraviolet?

Photodiodes and fluorescent materials

What detects x-rays?

Photographic film and photodiodes

What detects gamma rays?

A Geiger-Muller tube and counter and photodiodes

What are radio waves used for?

TV signals and telecommunications

What are microwaves used for?

Cooking food and telecommunications

What is infrared radiation used for?

Remote controls

What is visible light used for?

Lasers and fibre optics

What is ultraviolet radiation used for?

Detecting counterfeit bank notes, sterilising medical equipment, and treating skin conditions

What are x-rays used for?

Detecting broken bones and scanning luggage at airports

What is gamma radiation used for?

Cancer treatment, medical tracers, and sterilisation of medical equipment

What is diffraction?

When waves bend to pass through a gap or around a barrier

What is refraction?

When waves pass from one medium to another and change speed; they also change direction if the angle of incidence is greater than 0°

What happens when light passes from a less dense medium to a more dense medium?

The speed decreases, the frequency stays the same, the wavelength decreases, and the angle of refraction is less than angle of incidence when angle of incidence is greater than 0^o

What happens when light passes from a more dense medium to a less dense medium?

The speed increases, the frequency stays the same, the wavelength increases, and the angle of refraction is greater than angle of incidence when angle of incidence is greater than 0^o

Why does the wavelength of light decrease in a more dense medium?

Because the light’s speed decreases but the frequency remains constant, so the wavelength must decrease to maintain proportionality according to the equation v = fλ

Why does the wavelength of light increase in a less dense medium?

Because the light’s speed increases but the frequency remains constant, so the wavelength must increase to maintain proportionality according to the equation v = fλ

What is the normal in terms of refraction?

The normal is a dotted line drawn perpendicular to the surface where light enters a new medium

What is the angle of incidence?

The angle measured between the normal and the incident ray

What is the angle of refraction?

The angle measured between the normal and the refracted ray

What is the incident ray?

The ray going into the new medium

What is the refracted ray?

The path light takes after entering a new medium

What stays the same when light enters a new medium?

The frequency

What effect does increasing the wavelength have on diffraction?

Longer wavelengths diffract more than shorter wavelengths

When light travels from a less dense medium to a more dense medium, how does it bend?

Towards the normal

When light travels from a more dense medium to a less dense medium, how does it bend?

Away from the normal

What is total internal reflection?

When light, after hitting the boundary between the two media, does not refract into the second medium, but is reflected back into the current medium

What is the critical angle?

The minimum angle at which total internal reflection occurs

What principle does fibre optics use to transmit signals over large distances?

Total internal reflection