Communication System — Physics STD 12 Science — Question

The limit of resolution of eye is approximately:

When air in a capacitor is replaced by a medium of dielectric constant K, the capacity

(a) Decreases K times

(b) Increases K times

(c) Increases  times

(d) Remains constant

The vecter term of coulomb's law is :

A thin equiconvex lens is made of glass of refractive index 1.5 and its focal length is 0.2 m, if it acts as a concave lens of 0.5 m focal length when dipped in a liquid, the refractive index of the liquid is

(a)

(b)

(c)

(d)

Raman effect shows:

Which relation is correct for the power of compound microscope ?

The velocity of emitted electrons in photelectric effect depends :

Ten grams of ⁵⁷Co kept in an open container beta-decays with a half-life of 270 days. The weight of the material inside the container after 540 days will be very nearly:

The distance of two points on the axis of a magnet from its centre is 10 cm and 20 cm respectively. The ratio of magnetic intensity at these points is 12.5 : 1. The length of the magnet will be

(a) 5 cm

(b) 25 cm

(c) 10 cm

(d) 20 cm

Ray diverging from a point source from a wave front that is

(a) Cylindrical

(b) Spherical

(c) Plane

(d) Cubical