Magnetism And Matter — Physics STD 12 Science — Question

A point P is situated on the axis of an electric dipole at a distance x from its mid-point, the electric potential at point P is proportional to:

The neutron was discovered by:

If a magnetic substance is kept in a magnetic field, then which of the following is thrown out

(a) Paramagnetic

(b) Ferromagnetic

(c) Diamagnetic

(d) Antiferromagnetic

A converging lens is used to form an image on a screen. When upper half of the lens is covered by an opaque screen

(a) Half the image will disappear

(b) Complete image will be formed of same intensity

(c) Half image will be formed of same intensity

(d) Complete image will be formed of decreased intensity

A transformer is employed to

(a) Obtain a suitable dc voltage	(b) Convert dc into ac
(c) Obtain a suitable ac voltage	(d) Convert ac into dc

When stopping potential is applied in an experiment on photoelectric effect, no photocurrent is observed. This means that:

1. The emission of photoelectrons is stopped.
2. The photoelectrons are emitted but are reabsorbed by the emitter metal.
3. The photoelectrons are accumulated near the collector plate.
4. The photoelectrons are dispersed from the sides of the apparatus.

The angle of incidence at which reflected light is totally polarized for reflection from air to glass (refraction index n) is

(a)

(b)

(c)

(d)

According to classical theory, path of electron in Rutherford model :

A current flows in a conductor from east to west. The direction of the magnetic field at a points above the conductor is .....

(a) Towards north

(b) Towards south

(c) Towards east

(d) Towards west

When Silicon is dopped with Boron as an impurity the resulting substance is :