Ray Optics Test...

An isotropic source of 2 candela produces a light flux equal to

A lamp rated at 100 Cd hangs over the middle of a round table with a diameter of 3 metre at a height of 2 metre. It is replaced by a lamp of 25 Cd and the distance to the table is changed so that the illumination at the centre of the table remains as before. The illumination at the edge of the table becomes X time the original. Then X is

A screen is illuminated by two point sources A and B. Another source (sends a parallel beam of light towards P on the screen. The lines AP, BP and CP are 3 m, 1.5 m and 1.5 m respectively, Fig. The radiant powers of sources A and B are 90 W and 180 W resp. The beam coming from C is of intensity 20 W/m². The intensity at point P on screen due to source a will be

The illuminance of a surface 2 m away from a point source is 4 W/m². It will be 2 W/m² when the distance of the point from the source is

The frequency of e.m. wave which is best suited to observe a particle of radii 3 × 10^–4 cm is of the order of

If the speed of red light is denoted by V_r and the speed of violet light V_u then for vacuum

A plane mirror is approaching you at 5 cm. per second. You can see your image in it. At what speed will your image approach you?

A convex mirror of focal length f produces an image (1/n) th of the size of the object. The distance of the object from the mirror is

When light wave suffers reflection, at the interface between air and glass, the change of phase in the reflected wave is equal to

A thin convergent glass lens (µ_g = 1.5) has a power of + 5.0 D. When this lens is immersed in a liquid of refractive index µ, it acts as a divergent lens of focal length 100 cm. The value of µ must be