When an object is viewed with a light of wavelength 6000 under a microscope, its resolving power is 104. The resolving power of the microscope when the same object is viewed with a light of wavelength 4000 , is
104
2 × 104
1.5 × 104
3 × 104
Secondary rainbow in the atmosphere is
the result of polarization and dispersion of light
brighter than the primary rainbow
formed due to two reflections in the rain drop
formed with red colour on the top
If the radius of curvature of the curved surface of a plano -convex lens is 50 cm, its focal length is (µ =1.5)
0.5 m
0.75 m
1 m
0.25 m
The magnification of an image by a convex lens is positive only when the object is placed
at its focus F
between F and 2F
at 2F
between F and optical centre
A ray of light is incident normally on one refracting surface of an equilateral prism. If the refractive index of the material of the prism is 1.5, then
the emergent ray is deviated by 30°
the emergent ray is deviated by 60°
the emergent ray just graces the second reflecting surface
the ray undergoes total internal reflection at second refracting surface
B.
the emergent ray is deviated by 60°
The ratio of sine of the angle of incidence to sine of angle of refraction (r) is a constant called refractive index.
i.e, (a constant). For two media, Snell's Law can be written as,
Given, Refractive index of a prism
Angle of incidence > critical angle
So, total internal reflection takes places at second refracting surface.
An aperture of size a is illuminated by a parallel beam of light of wavelength λ. The distance at which ray optics has a good approximation is
Two plane wavefronts of light, one incident on a thin convex lens and another on the refracting face of a thin prism. After refraction at them, the emerging wavefronts respectively become
plane wavefront and plane wavefront
plane wavefront and spherical wavefront
spherical wavefront and plane wavefront
spherical wavefront and spherical wavefront
Identify the wrong sign convention.
The magnification for virtual image formed by a convex lens is positive.
The magnification for real image formed by a convex lens is negative
The magnification for virtual image formed by a concave lens is negative
The distances measured in the direction of incident light is positive
The apparent flattening of the sun at sunset and sunrise is due to
refraction
diffraction
total internal reflection
interference