The Effect of Path Difference

Q.

The velocity of waves in a string fixed at both ends is 2 m/s. The string forms standing waves with nodes 5.0 cm apart. The frequency of vibration of the string in Hz is

[SCRA 1998]

1. 40

2. 30

3. 20

4. 10

Q.

A stretched string of length I, fixed at both ends can sustain stationary waves

of wavelength $\lambda$ given by

[UPSEAT 2000; Pb. PET 2004; CPMT 2005]

1. 

2. 

3. 

4. 

Q.

The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by

1. Planck's law of radiation

2. Stefan's law of radiation

3. Wien's law

4. Rayleigh jeans law

Q.

Beats are the result of

[CPMT 1971; J & K CET 2002]

1. Diffraction

2. Destructive interference

3. Constructive and destructive interference

4. Superposition of two waves of nearly equal frequency

Q.

Motion of water in a vertical U - tube is SHM when water on one side is depressed a little and then released. Calculate the angular frequency of vibrations when height of water in U tube is 0.9 m.

1. 3.14s

2. 3.34s

3. 3.5s^-1

4. 3.34s^-1

Q. The point S is monochromatic source of light emitting light of wavelength $\lambda .$ At the point P at a distance x from the mirror as shown in the figure, interference takes place between two light rays one directly coming from source S and another after reflection from the mirror such that a maxima is formed. The value of x may be:

1. $120\lambda$
2. $125\lambda$
3. $62.5\lambda$
4. $187.5\lambda$

Q.

When two sound waves with a phase difference of $\frac{\pi }{2}$, and each having amplitude A and frequency ω, are superimposed on each other, then the maximum amplitude and frequency of resultant wave is [MP PMT 1989]

1. 

2. 

3. 

4. 

Q. 140 Three sources of light A, B and C produce intensities 4I , 9I and 16I at a point P when they are switched on independently. Light from A and B are coherent and have a phase difference pi / 3 at the point P while source C, emitting at same frequency, is in coherent.The total intensity at P

Q. Why for constructive interference Maximum Intensity is four times the original

Q.

When one of the slits in Young's experiment is covered with a transparent sheet of thickness $3.6\times {10}^{-3}$ cm the central fringe shifts to a position originally occupied by the 30th brigth fringe. If $\lambda =6000A,$ the refractive index of the sheet is

1. 1.5
2. 1.55

3. 1.60

4. 1.65