Waves and electromagnet spectrum

What is a wave

a wave transfers energy and information without transferring matter

Transverse wave

A wave where the oscillations are perpendicular to the direction of energy transfer-water, light

Longitudinal wave

a wave where the oscillations are parallel to the direction of energy transfer- sound, ultrasound

amplitude

The height of a wave, measured from the midpoint

Wavelength

the distance from peak to peak-shortest distance between repeating parts if a wave

frequency

The number of waves passing a fixed point per second

Time period

the time it takes for one wave to pass a fixed point

Wavefront

a line that represents the peak of a wave

Equation involving frequency, wavelength and wave speed

Wave speed(m/s)=frequency(Hz) x wavelength(m)

v=f x lamda

Equation involving time period, 1 and frequency

Frequency(Hz)=1/Time period (s)

doppler effect

the change in pitch or frequency of a sound or light wave as the source or observer moves

What happens when a wave is moving towards you

• The wavelength is shorter, so the frequency is higher

• Wave speed stays the same

• It would appear higher pitch or more blue

What would happen if a wave is moving away from you

• Wavelength is longer, the frequency is lower

• wave speed stays the same

• it would appear low pitched or more red

Similarities of EM waves

• Travel through a vacuum

• Travel at the same speed in a vacuum

• Transverse waves

• Transfer energy and information, but not matter

Differences in EM waves

• Different wavelengths

• Different frequency’s

• Different amounts of energy

What are all the waves in the EM spectrum

• Radio

• microwaves

• infrared

• visible light

• ultraviolet

• X-rays

• Gamma

Which wave has the longest wavelength

radio waves

Which wave has the highest frequency

gamma rays

Which wave has the highest energy

Gamma rays

Which colour has the highest frequency

violet

Which colour has the longest wavelength

red

what are 2 uses for radio?

• Communication

• TV and radio signals

What is a danger of radio?

no proven dangers

What are 2 uses for microwaves

• Satellite communication

• cooking

What are the dangers of microwaves

• Internal heating of tissue

What are the uses of infrared

• Cooking

• Heat treatment of illness

• thermal imaging

What are the dangers of infrared

skin burns

What are the uses of visible light

• Photography

• fibre optics

• endoscopes

What are the dangers of visible light

damage to retinas

What are the uses for UV

• Fluorescent lamps

• detecting forgery

• tanning beds

What are the dangers of UV

skin cancer, and damage to eyes

What are the uses of X-rays

• Medical imaging

• Airport scanners

What are the dangers of X-rays

Kill living tissues and cause cell mutations which lead to cancer

What are the uses of Gamma rays

• Sterilising medical equipment

• Killing cancer calls (radiotherapy)

What are the dangers of gamma rays

can kill living tissues and causes cell mutations due to ionisation-leads to cancer