Electromagnetic Spectrum

Question 1

What is the electromagnetic spectrum

Answer 1

The electromagnetic spectrum is arranged in a specific order based on the wavelengths or frequencies
They all travel through a vacuum and all have the same speed in air (3 x 10^8)
The main groupings of the continuous electromagnetic (EM) spectrum are:

Question 2

What are the main groupings for electromagnetic spectrum

Answer 2

The main groupings of the continuous electromagnetic (EM) spectrum are:
Radio waves (low frequency, high wavelength, low energy of radiation)
Microwaves
Infrared
Radiation
Visible (red, orange, yellow, green, blue, indigo, violet)
Ultraviolet
X-rays
Gamma rays (high frequency, low wave length, high energy of radiation)

High energy of radiation, is highly ionising and very dangerous
Low energy of radiation, is useful for communication and not dangerous

Question 3

Electromagnetic waves in a vacuum

Answer 3

All electron magnetic waves can go through a vacuum at the same speed of 3.0 x 10^8 m/s (its roughly the same in air)

Question 4

Uses of electromagnetic waves

Answer 4

Radio waves - radio and televising communications
Microwaves - satellite communication And microwaves
Infrared radiation - remote controllers and infrared cameras
Visible light - vision, photography
Ultra violet light - tanning beds
X rays - medical imaging and security
Gamma radiation- medical treatment

Question 5

Hazards of electromagnetic waves

Answer 5

Ultra violet - skin cancer
X rays and gamma rays - mutations causing cancer
Microwaves - internal heating o f body tissue
Infrared radiation can cause skin burns

Question 6

Communication using electromagnetic spectrum

Answer 6

Communication with artificial satellites is used mainly by microwaves

Some satellite phones use low orbit artificial satellites

Some satellites phones and direct broadcast satellites television use geostationary satellites

Question 7

Systems using radio waves and microwaves

Answer 7

• mobile phones, wireless internet use microwaves because it can penetrate some walls and only require short aerial for transmissions and reception
• Bluetooth uses low energy radio waves or microwaves because they can pass through walls but the signal is weakened in doing so
  -optical fibres(visible light/infrared), used for cables television and high speed broad band they can carry high rates of data

Question 8

Digital and analogue signals

Answer 8

Analogue signals can vary continuously they can take any value
Digital signal can only take one or two discrete states
(1s and 0s, highs and lows, ons and offs)
This makes it easier to transmit
Sound waves can be transmitted as digital or analogue signals

Question 9

Advantages of digital signallling

Answer 9

• The signal can be regenerated so there is minimal noise
• Due to accurate signal regeneration, the range of digital signals is larger than the range of analogue signals (they can cover larger distances)
• Digital signals enable an increased rate of transmission of data compared to analogue
• Extra data can be added so that the signal can be checked for errors

Question 10

Eclipse

Answer 10

When an eclipse of the sun happens all radiation disappear at the same time