Nuclei — Physics STD 12 Science — Question

The  main source of solar energy is

(a) Fission reactions	(b) Fusion reactions
(c) Chemical reactions	(d) Combustion reactions

The device is based on the principle of mutual induction is:

Mark the incorrect statement.

A coil of inductance L is carrying a steady current i. What is the nature of its stored energy

(a)  Magnetic	(b)  Electrical
(c)  Both magnetic and electrical	(d)  Heat

In a Wheatstone’s bridge all the four arms have equal resistance R.  If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is

(a)

(b) R

(c) 2R

(d)

The ratio of the longest to shortest wavelengths in Brackett series of hydrogen spectra is

(a)

(b)

(c)

(d)

Assertion   :  Coloured spectrum is seen when we look through a muslin cloth.

Reason       : It is due to the diffraction of white light on passing through fine slits.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

An ionization chamber with parallel conducting plates as anode and cathode has 5  electrons and the same number of singly-charged positive ions per . The electrons are moving at 0.4 m/s. The current density from anode to cathode is .  The velocity of positive ions moving towards cathode is

(a) 0.4 m/s

(b) 16 m/s

(c) Zero

(d) 0.1 m/s

Which of the following sometimes requires initiation from a neutron?

When a plane wavefront is incident on a thin conver lens, the emerging wavefront becomes ___________