Electromagnetic waves

Question 1

electromagnetic waves

Answer 1

. electric and magnetic disturbances that can be used to transfer energy from a source to an absorber
. they do not transfer matter
. energy transferred = wavelength of wave

Question 2

microwave ovens

Answer 2

energy is transferred from a microwave source to the food in the oven, heating it

Question 3

radiant heaters

Answer 3

infrared radiation transfers energy from the heater to heat the surroundings

Question 4

Waves from longest to shortest wavelength:

Answer 4

1. radio waves
2. microwaves
3. infrared radiation
4. visible light
5. ultraviolet radiation
6. gamma rays

Question 5

Speed that electromagnetic waves travel in through space or in a vacuum

Answer 5

3.0 * 10^8 m/s

Question 6

Equation for wave speed

Answer 6

wave speed = frequency * wavelength

Question 7

The shorter the wavelength of the wave, the …… the frequency

Answer 7

higher

Question 8

The energy of the waves increases as the ……… increases

Answer 8

frequency

Question 9

White light

Answer 9

Light from ordinary lamps and from the Sun

Question 10

The hotter an object is, the …. infrared radiation it emits

Answer 10

more

Question 11

Dangers of infrared radiation

Answer 11

. It can be absorbed by the skin
. It can damage, burn or kill skin cells because it heats up the cells

Question 12

Use of Infrared radiation

Answer 12

. Optical fibres in communications because infrared radiation is absorbed less than visible light in the glass fibres
. Remote controls send out a sequence of infrared pulses when you press a button which can be easily produced and detected