Waves

What are waves? A wave is a phenomenon in which

energy is transferred through vibration.

Types of Waves Transverse Waves

Longitudinal Waves

Transverse Waves are waves which travel in a direction

perpendicular to the direction of vibrations.

Direction of vibrations

Direction of wave

Generating Transverse Waves

Transverse Wavesexamples include

water wavesrope waveslight waveelectromagnetic waves

Longitudinal Waves are waves which travel in a direction parallel to

the direction of vibrations.

Direction of vibration

Direction of wave

examples includesound wavessound waves

Generating of Longitudinal Waves [slinky spring]

Characteristics of A Wave Crests and Troughs Amplitude Wavelength Frequency Period Speed

Crests and Trough Crests are high point of a wave Troughs are low point of a wave

displacement

distance

crest crest

troughtrough

Amplitude (A) is the height of a crest or depth of a

trough measured from the normal undisturbed positions.

displacement

distance

crest crest

trough

Amplitude

Amplitude

SI Unit For Amplitude is measured in metres (m)

displacement

distance

crestcrest crestcrest

trough

Amplitude

Amplitude

Wavelength () is the distance between two

successive crests or troughsdisplacement

distance

Amplitude

AmplitudeAmplitude

crestcrest crest

trough trough

Wavelength

Wavelength

SI Unit For Wavelength is measured in metres (m)

displacement

distance

Amplitude

Amplitude

crestt crest

trough trough

Wavelength

Frequency (f) is the number of vibrations in one

second.

SI Unit For Frequency is the Hertz (Hz)

1 Hz is 1 vibration in 1 second.

50 Hz is 50 vibrations in 1 second.

Test Yourselves Explain the meaning of

28 Hz, 100 Hz , 135 Hz, 1570 Hz.

Period (T) is the time taken for one complete

vibration. (or oscillation or cycle)

SI Unit For Period is measured in second (s)

Relationship between Period (T) and Frequency (f)

f = 100 Hz T = 1/100 s f = 40 Hz T = 1/40 s f = 23 Hz T = 1/23 s f = 8 Hz T = 1/8 s f = f Hz T = 1/f s

Relationship Between f and T

f1T

Speed Of a Wave is the distance moved in one second.

SI Unit For Speed is measured in metre per second (ms-1or m/s)

Wave Equation Speed of a wave

= wavelength period= wavelength x frequency

where v = speed, f = frequency and = wavelength V = f

Describing WavesDisplacement-Time Graph

for one particle on the wave

timetime

displacementdisplacement