EM Waves

What are electromagnetic waves?

Transverse waves that transfer energy from the source of the waves to an absorber.

What wave has the lowest energy?

Radio waves

What wave has the longest wavelength?

Radio waves

What wave has the highest frequency?

Gamma rays

What are the problems associated with radiation with higher energy?

Highly ionising and harmful to cells and tissues causing cancer.

What is visible light?

The range of wavelengths which are visible to humans.

What colour has the shortest wavelength?

Violet

How do EM waves transfer energy by microwaves?

Water molecules absorb certain wavelengths of microwave radiation so microwaves transfer energy by radiation to the thermal store of the food.

How do EM waves transfer energy by Infared?

Hot objects emit infrared radiation so the waves can be absorbed by other objects.

What type of EM radiation does the sun emit?

Visible light, Ultraviolet and Infared.

What is the method for the investigating IR RQP?

1. Set up four identical flasks painted black, grey, white and silver.

2. Fill the flasks with hot water ensuring they have the same initial temperature.

3. Note the starting temperature and measure the temperature at regular intervals.

What does the intensity of emitted radiation depend on?

Temperature, hotter objects emit more thermal radiation, surface area and the colour of the surface.

What colour is the best emitter?

Black

What colour is the worst emitter?

Silver

How do atoms interact with EM waves?

Absorbed and emitted

What happens if an electron absorbs an EM wave?

The electron moves up to a higher energy level.

What happens if an electron moves down an energy level?

It will emit an EM wave in the process.

What EM waves are associated with electron transitions?

Visible light and Ultraviolet.

How are radio waves produced?

Oscillations in electrical circuits, when radio waves are absorbed by a conductor they create an alternating current which has the same frequency as the radio waves, information can be decoded as the wave is received.

What are the danger of microwaves?

Possible heat damage to organs.

What are the dangers of infrared?

Skin burns

What are the dangers of visible light?

Bright light can cause eye damage.

What are the dangers of ultraviolet?

Eye damage, sunburn and skin cancer.

What are the dangers of X-rays and gamma rays?

Kills cells, mutations and cancer.

What can microwaves be used for and why?

Communications and heating food because they can penetrate earth’s atmosphere

What are radio waves used for and why?

Communication because they can be reflected from earth’s atmosphere.

What is infrared used for and why?

Remote control, fibre optic communications and night vision cameras because the can undergo total internal reflection.

What is visible light used for?

Seeing and taking videos or photographs

What is ultraviolet used for?

Security marking, fluorescent bulbs and tanning.

What are X-rays used for and why?

X-ray imaging in hospitals and airports because they can penetrate soft tissues but no bone.

What are gamma rays used for and why ?

Sterilising medical instruments and treating cancer because gamma rays kill cells and bacteria.

What are the parts of the electromagnetic spectrum?

Microwaves, radio waves, infrared radiation, visible light, ultraviolet, X-rays, gamma rays

How do X-rays work?

The X-rays are absorbed by dense structures so appear white and soft tissues allow x-rays to pass through so appear darker.