Ray Optics and Optical Instruments — Physics STD 12 Science — Question

A condenser of capacitance 10 μF has been charged to 100 volts. It is now connected to another uncharged condenser in parallel. The common potential becomes 40 volts. The capacitance of another condenser is

(a) 15 μF

(b) 5 μF

(c) 10 μF

(d) 16.6 μF

In Young’s double slit experiment, the central bright fringe can be identified

(a) By using white light instead of monochromatic light

(b) As it is narrower than other bright fringes

(c) As it is wider than other bright fringes

(d) As it has a greater intensity than the other bright fringes

Two lithium nuclei in lithium vapour at room temperature do not combine to form a carbon nucleus because:

Consider the situation shown in figure. The wire AB is slid on the fixed rails with a constant velocity. If the wire AB is replaced by a semicircular wire, the magnitude of the induced current will: 

1. Increase.
2. Remain the same.
3. Decrease.
4. Increase or decrease depending on whether the semicircle bulges towards the resistance or away from it.

For photoelectric emission, tungsten requires light of 2300 Å. If light of 1800 Å wavelength is incident then emission

(a) Takes place	(b) Don’t take place
(c) May or may not take place	(d) Depends on frequency

If an electric dipole is placed in an electric field, then the value of the torque acting on it will be:

Li nucleus has three protons and four neutrons. Mass of lithium nucleus is 7.03.6005 amu. Mass of proton is 1.007277 amu and mass of neutron is 1.008665 amu. Mass defect for lithium nucleus in amu is:

When an impurity is doped into semiconductor, the conductivity of the semiconductor:

A thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat glass plae as shown in figure. The observed interference fringes from this combination shall be: