A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will
become small, but non-zero
remain unchanged
become zero
become infinite
Rainbows are formed by
reflection and diffraction
refraction and scattering
dispersion and total internal reflection
interference only
One face of a rectangular glass plate 6 cm thick is silvered. An object held 8 cm in front of the first face, forms an image 12 cm behind the silvered face. The refractive index of the glass is
0.4
0.8
Time taken by sunlight to pass through a window of thickness 4 mm whose refractive index is is
2 × 10-4s
2 × 108s
2 × 10-11s
2 × 1011s
Which of the following phenomenon is not common to sound and light waves?
Interference
Diffraction
Coherence
Polarisation
The refractive index of the material of the prism is √3, then the angle of minimum deviation of the prism is
30°
45°
60°
75°
Which of the following phenomena exhibits particles nature of light?
multiple total internal reflections
A transparent cube contains a small air bubble. Its apparent distance is 2 cm when seen through one face and 5 cm when seen through other face. If the refractive index of the material of the cube is 1.5, the real length of the edge of cube must be
7 cm
7.5 cm
10.5cm
Ray optics is valid, when characteristic dimensions are
of the same order as the wavelength of light
much smaller than the wavelength of light
of the order of one millimetre
much larger than the wavelength of light
A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness 3cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again?
1 cm upward
4.5 cm downward
1 cm downward
2 cm upward
