WAVE MOTION & SOUND -2

Time period - Frequency - wave velocity

Phase: 

The points on a wave which are in the same state of vibration are said to be in the same phase

In the following figure wave A and B are in same phase but C is no in same phase of Aor B

Time period: 

the time in which a vibrating body completes one vibration is called time period

(Or)

Time required to produce one complete wave or cycle

Units: second (s) ---- S.I system

Frequency(f or υ) : 

Number of complete waves or Cycles produced in one second

(Or)

Number of vibrations per second

Frequency= no.of Cycles / time

Unit: hertz (Hz) ----- S.I system 

Hertz: 

One hertz is equal to one vibration per one second 

One  hertz = one vibration / one second

                    = 1 Hz

Frequency is constant for all media in which wave form passes

Wave length: 

Wave length is equal to the length of one  wave or cycle.

The distance travelled by wave in one time period

The distance between two nearest particles which are in the same phase 

Denoted by Greek letter lambda ( λ ) 

Units of wavelength:  meter (m)

Wave velocity (velocity of wave): 

The distance travelled by a wave in one second is called the velocity of wave.

Represented by 'v'

Wave velocity = distance travelled/ time taken

Unit: m/s

Amplitude(A):

The maximum displacement of the particle of a medium from their mean position during the propagation of a wave

Represented by letter 'A'

Amplitude of wave is measure of its energy 

Unit: meters (m)

Relation between time period (T) and frequency (f):

Frequency of wave is reciprocal of its time - period

Frequency = 1/time period

f = 1/T or T = 1/f

Relation between time period (T) wave length (λ) and  velocity (v):

We know wave velocity = distance travelled by wave/ time

                    V= λ/T 

                    V= λ .f.            ∵ f = 1/T

                    f = V/λ  (or) λ = V/f  

Question-1

The velocity of sound in air is 344 m/s. What is the wavelength of a sound wave of frequency 32Hz?

Question-2

A wave travels at a speed 330 m/s. If wave length is 2.2 C.M. what will be the frequency of the wave?

Question-3

A wave travels at a speed of radio waves frequency 10⁹ Hz. The speed of radio waves is 3×10⁸ m/s

Question-4

The velocity of sound in air is 340 m/s. Then ______ m is the wavelength of sound wave of frequency 34Hz?

Question-5

A wave of wave length 0.60 cm is produced in air and travels at a speed 300 m/s. Then the frequency will be ?

Question-6

A tuning forc produces 256 waves in 2 seconds. Calculate the frequency  of tuning fork?