Explanation:
As fringe width is proportional to the wavelength and wavelength of light is inversely proportional to the refractive index of the medium,
Here,
$\lambda_\text{M}=\frac{\lambda}{\eta}$
$\lambda_\text{M}$ = wavelength in medium
$\lambda$ = wavelength in vacuum
$\eta$ = refractive index of medium
Hence, fringe width decreases when Young's double slit experiment is performed under water.
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Figure shows three points A, B and C in a region of uniform electric field 
. The line AB is perpendicular and BC is parallel to the field lines. Then which of the following holds good. Where 
and 
represent the electric potential at points A, B and C respectively
|
(a) |
(b) |
(c) |
(d) |
A piece of cloud having area 25 
and electric potential of 
volts. If the height of cloud is 0.75 km, then energy of electric field between earth and cloud will be
|
(a) 250 J |
(b) 750 J |
(c) 1225 J |
(d) 1475 J |
The net resistance of a voltmeter should be large to ensure that
|
(a) It does not get overheated |
|
(b) It does not draw excessive current |
|
(c) It can measure large potential difference |
|
(d) It does not appreciably change the potential difference to be measured |
The focal length of a normal eye-lens is about:
Two radioactive materials 
and 
have decay constants 10λ and λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of to that of will be 1/e after a time
|
(a) 1/(10 λ) |
(b) 1/(11 λ) |
(c) 11(10 λ) |
(d) 1(9 λ) |
In which of the following remote sensing technique is not used
|
(a) Forest density |
(b) Pollution |
(c) Wetland mapping |
(d) Medical treatment |
