Electric Charges and Fields — Physics STD 12 Science — Question

The electric flux on a Gaussian spherical surface of radius 15 cm, drawn with a point charge as the centre, is ф. If the radius of this surface is tripled, then the electric flux passing through the surface will be:

The stopping potential is directly related to:

A combination of two thin lenses of the same material with focal lengths  and , arranged on a common axis minimizes chromatic aberration, if the distance between them is

(a)

(b)

(c) (

(d)

A horizontal circular loop carries a current that looks clockwise when viewed from above. It is replaced by an equivalent magnetic dipole consisting of a south pole S and a north pole N:

1. The line SN should be along a diameter of the loop.
2. The line SN should be perpendicular to the plane of the loop.
3. The south pole should be slow the loop.
4. The north pole should be below the loop.

The penetrating power of X-rays depends upon :

When an atomic gas or vapour is excited at low pressure, by passing an electric current through it then?

The continuous x-ray spectrum obtained from a Coolidge tube is of the form

(a)

(b)

(b)

(d)

X-ray beam can be deflected:

The effective capacitance between the points P  and  Q  of the arrangement shown in the figure is

(a)

(b) 1

(c) 2

(d) 1.33

The radioactive nucleus  decays to   through the emission of

(a) Neutron

(b) Proton

(c) Electron

(d) Positron