revision sound. doppler effect doppler effect as the change in frequency (or pitch) of the sound...

REVISIONSOUND

DOPPLER EFFECT• Doppler effect as the change in frequency (or

pitch) of the sound detected by a listener because the sound source and the listener

have different velocities relative to the medium of sound propagation

𝑓 𝐿=𝑣±𝑣 𝐿

𝑣±𝑣𝑆

𝑓 𝑆

FORMULA

𝑓 𝐿=𝑣±𝑣 𝐿

𝑣±𝑣𝑆

𝑓 𝑆Frequenc

y of listener

Frequency of

sourceSpeed of source

Speed of listener

Speed of sound in medium

Speed of sound in medium

f

APAR

T

𝑓 𝐿=𝑣±𝑣 𝐿

𝑣±𝑣𝑆

𝑓 𝑆+-

f

TOW

ARD EACH

OTH

ER

𝑓 𝐿=𝑣±𝑣 𝐿

𝑣±𝑣𝑆

𝑓 𝑆+-

ELECTROMAGNETIC SPECTRUM

light wavesIt does NOT need a medium to propagate

It consists of seven main groups

DOPPLER EFFECT with LIGHT

DOPPLER EFFECT with LIGHT

DOPPLER EFFECT with LIGHT

DOPPLER EFFECT with LIGHT

-1

Dolphins use ultrasonic waves to explore their surroundings.

When a dolphin is 100m from a rock, it emits an ultrasonic wave

with a frequency of 250 kHz,

while swimming at 20m.s towards the rock.

Assu

-1

.

a Calculate the frequency of the sound waves that reach the rock

b When the dolphin is 50m from the rock, i

me that the speed of sound

t emits another wave

of 25

in water is

0 kHz .

How do

1500m.

es

s .

this preceived frequency relate to the answer is a)

GENERAL DOPPLER EFFECT

 The siren of a stationary ambulance emits ound

with a frequency of 700 Hz.

The driver of a car approaches the ambulance and

then passes it by. He perceives that the frequency

of the siren changes by

s

-1

a Name and state the wave phenomena

b Take the speed of sound in air as 340m.s and

calculate the speed of the car when it passes

the ambul

80Hz

ance

CHANGES IN FREQUENCY

a)

b)