A linear object is placed along the axis of a mirror as shown in fig. If ‘f’ is the focal length of the mirror then the length of image is 

A clock hung on a wall has marks instead of numerals on its dial. On the adjoining wall, there is a plane mirror and the image of the clock in the mirror indicates the time 7 : 10. Then the time on the clock is :

A short linear object of length L lies on the axis of a spherical mirror of focal length ƒ at a distance u from the mirror. Its image has an axial length L’ equal to :

When a light ray enters refracting medium, it is found that the magnitude of the angle of refraction is equal to half the angle of reflection. If n is the refractive index of the medium, then the angle of incidence is :

A ray of light is incident on the surface of separation of a medium at an angle 45° and is refracted in the medium at an angle 30°, What will be the velocity of light in the medium ?

A ray of light passes through four transparent media with refractive indices μ1, μ2, μ3 and μ4 as shown in the given figure.
The surfaces of all media are parallel. If the emergent ray CD is parallel to the incident ray AB, we must have :

Two mirrors at an angle θ produce 5 images of a point. The number of images produced when θ is decreased to 30° is

If the lower half of a concave mirror’s reflecting surface is made opaque, which of the following statements describe the image of an object placed in-front of the mirror

S1 : Intensity of the image will increase.
S2 : The image will show only half of the object.
S3 : No change in the image.
S4 : Intensity of the image will be reduced to half.

A rectangular tank of depth 8 meter is full of water (μ = 4/3), the bottom is seen at the depth

A beam of light is converging towards a point I on a screen. A plane glass plate whose thickness in the direction of the beam = t, refractive index = μ, is introduced in the path of the beam. The convergence point is shifted by