4 / 6 • Standing Waves / Doppler Effect

Define Standing Wave

Two waves of the same frequency and amplitude travelling in opposite directions

Label This Diagram

The Stationary Wave

a - node

b - antinode

Define Resonance

The transfer of energy between bodies of the same natural frequency

Define Doppler Effect

The apparent change in the frequency of a wave due to the motion of the source or observer

Label This Diagram

The Doppler Effect

a - observer

b - crest 1

c - crest 2

d - crest 3

s - source

Label This Formula

The Doppler Effect

f’ - apparent frequency

f - actual frequency

c - speed of wave

u - speed of source

+ - source moving away

- - source moving towards

What page of the log tables can you find the Doppler Effect Formula?

59

Demonstrate the doppler effect • 1

• Mount a buzzer of a single frequency on a string

• Turn on buzzer

• Observed frequency = source frequency

Demonstrate the doppler effect • 2

• Spin string

• Observed frequency increases and decreases

Name 3 applications of the Doppler Effect

• Garda speed guns

• Red shift of stars - measures their speed

• Train passing under a bridge