Nuclei — Physics STD 12 Science — Question

A metallic loop is placed in a magnetic field. If a current is passed through it, then

(a) The ring will feel a force of attraction

(b) The ring will feel a force of repulsion

(c) It will move to and fro about its centre of gravity

(d) None of these

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)

A silicon speciman is made into a P-type semi-conductor by dopping, on an average, one Indium atom per 5  silicon atoms. If the number density of atoms in the silicon specimen is 5   then the number of acceptor atoms in silicon per cubic centimetre will be

(a) 2.5	(b) 1.0
(c) 1.0	(d) 2.5

The graph that correctly represents the relation of frequency n of a particular characteristic X-ray with the atomic number Z of the material is

(a)

(b)

(c)

(d)

Which of the following statement is false for the properties of electromagnetic waves?

The air film in a Newton's ring apparatus is replaced by an oil film. The radii of the rings:

In the circuit shown in figure the maximum output voltage V₀ is

(a) 0 V

(b) 5 V

(c) 10 V

(d)

If a positive charge is taken from a region of lower potential to a region of higher potential, then the electrical potential energy:

The valence of the impurity atom that is to be added to germanium crystal so as to make it a N-type semiconductor, is

(a) 6

(b) 5

(c) 4

(d) 3

Two protons are kept at a separation of 10nm. Let F_n and F_e be the nuclear force and the electromagnetic force between them:

1. F_e = F_n.
   
2. F_e >> F_n.
   
3. F_e << F_n.
   
4. F_e and F_n differ only slightly.