Tag: properties of waves

Questions Related to properties of waves

Crest or troughs in a travelling wave are

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. moving entities

  2. stationary entitites

  3. moving entities along +Y direction

  4. moving entities along -Y direction

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Correct Option: A
Explanation:

Crest and troughs are part of the waves and they will be  moving in the direction of the wave

The correct option is (a)

The distance between two consecutive crests or troughs are equal in a wave

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. True

  2. False

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Correct Option: A
Explanation:

The distance between two consecutive crests or troughs are equal in a wave and is known as the length of a wave or wavelength

Ocean waves of time period $0.01$ second have a speed $15 m/s$. What is the adjacent crest and the trough is:

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. $15 \times 10^{-2} m$

  2. $7.5 \times 10^{-2} m$

  3. $3.25 \times 10^{-2} m$

  4. $30 \times 10^{-2} m$

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Correct Option: B

The velocity of light in glass whose refractive index w.r.t air is $1.5$ is $2 \times 10^8 \,m/s$. In a certain liquid, the velocity of light is found to be $2.5 \times 10^8 \,m/s$. The refractive index of the liquid w.r.t air is

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. $0.8$

  2. $0.9$

  3. $1.2$

  4. $1.33$

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Correct Option: C
Explanation:
Velocity of light in glass $(v _1)=2\times 10^8 m/s$
Refractive index of glass $(\eta _1)=1.5$
w.r.t air
Velocity of light in certain $2\times 10^8\ m/s$
liquid $(v _2)$
Let refractive index of certain $=\eta _g$
liquid w.r.t air
Using formula,
$Refractive\ index=\dfrac{Velocity\ of\ light}{Velocity\ of\ light\ in\ med}$
we get
$\dfrac{\eta _1}{\eta _2}=\dfrac{V _2}{V _1}$
$\eta _2=\dfrac{\eta _1 V _1}{V _2} $
$\eta _2=\dfrac{31.5\times 2\times 10^8}{52.5\times 10^8}$
$\eta _2=\dfrac{6}{5}=1.2$
$\therefore$ Refractive index of certain liquid$=1.2$

If the distance between two successive troughs in a transverse wave is 8 cm, then the amplitude of that wave is 5 cm.

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. True

  2. False

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Correct Option: B
Explanation:

wavelength and amplitude are independent of each other so for any value of amplitude any wavelength can be possible .

so the answer  is B.

Water waves are:

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. Longitudinal

  2. Transverse

  3. Both Longitudinal and transverse

  4. Neither longitudinal nor transverse

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Correct Option: C
Explanation:

The water molecules displace along the propagation direction as well as along perpendicular direction. 

Hence, water waves are both longitudinal and transverse.

A transverse wave travelling on a taut string is represented by $y = 0.01 \sin 2 \pi ( 10 t - x )$ where y and x are in metre and t is in second. Then

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. The speed of the wave is 10 m/s.

  2. Closest points on the string which differ in phase by $60^o$ are $\dfrac16\ m$ apart.

  3. Maximum particle speed is $\frac { \pi } { 5 } { m } / { s }$

  4. The phase of a certain point on the string changes by $120 ^ { \circ }$ is $\dfrac1{20} $seconds

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Correct Option: A,B

What is the phase difference between two successive crests in the wave?

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. $\pi$

  2. $\frac{\pi}{2}$

  3. $2\pi$

  4. $4\pi$

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Correct Option: C
Explanation:

Phase difference between any two particles in a wave determines lack of harmony in the vibrating state of two particles, ie, how far one particle leads the other or lags behind the other. 
Relation of path difference and phase difference is given by
$\Delta \phi=\frac{2\pi}{\lambda}\times \Delta x$
where $\Delta x$ is path difference. 
But path difference between two crests
$\Delta x=\lambda$
Hence, $\Delta  \phi = \frac{2\pi}{\lambda}\times \lambda =2\pi$ 

The wave produced by a motor boat sailing in water are

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. Transverse

  2. Longitudinal

  3. Longitudinal and Transverse

  4. Stationary

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Correct Option: C
Explanation:

The waves produced by a motorboat sailing in water are of both transverse and longitudinal type. Transverse waves are produced on the surface and longitudinal waves are produced deep inside the water.

A crest is the point of maximum displacement of a particle in a wave. State whether true or false.

physics properties of waves longitudinal and transverse waves travelling waves types of waves

  1. True

  2. False

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Correct Option: A
Explanation:

A crest is a point on the wave with the maximum value of upward displacement within a cycle. A crest is a point on the surface wave where the displacement of the medium is the maximum.