CH11: Electromagnetic Waves

Question 1

what are electromagnetic waves (EM)?

Answer 1

transverse waves that do require a medium to travel. they are made up of oscillating electric and magnetic fields.

Question 2

what is the speed of EM waves in vacuum?

Answer 2

3.0 x 10^8 m/s

Question 3

what happens to the speed and wavelength of EM waves when it travels from a vacuum to any other medium?

Answer 3

the speed and wavelength decrease but frequency remains the same as the source.

Question 4

list the EM waves in increasing frequency order

Answer 4

radio wave, microwave, infrared, visible light, ultraviolet, x-rays, gamma rays

Question 5

effects of EM waves from being exposed to heat

Answer 5

too much UV radiation can cause sun burn which can cause skin cancer

Question 6

effects of EM waves from ionising radiation

Answer 6

ionising radiation can penetrate our bodies more easily than high energy particles which can result in a mutation of healthy cells into cancerous cells.

Question 7

what are the common uses of EM waves?

Answer 7

radio wave: radio and satellite communication, TV broadcast
microwave: microwave oven, wifi signals, radar
infrared: heating, short range data transfer, remote controls
visible light: artificial light for plants, data transfer in optical fibres
ultraviolet: sterilisation or killing bacteria and viruses
x-rays: medical imaging, find defects in manufactured part, carbon dating
gamma rays: radiotherapy, sterilisation