Alternating Current — Physics STD 12 Science — Question

The negative Zn pole of a Daniel cell, sending a constant current through a circuit, decreases in mass by 0.13g in 30 minutes. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is

(a) 0.242 g

(b) 0.190 g

(c) 0.141 g

(d) 0.126 g

Which law can ampere’s circuital be derived from?

What is moving coil galvanometer used for?

In an insulator, the energy gap between conduction band and valence band is about:

A block A kept on an inclined surface just begins to slide if the inclination is 30°. The block is replaced by another block B and it is found that it just begins to slide if the inclination is 40°:

1. Mass of A > mass of B.
2. Mass of A < mass of B.
3. Mass of A = mass of B.
4. All the three are possible.

In Young's double slit experiment how many maximas can be obtained on a screen (including the central maximum) on both sides of the central fringe if λ = 2000 and d = 7000  

(a) 12

(b) 7

(c) 18

(d) 4

For harder X-rays:

1. The wavelength is higher.
2. The intensity is higher.
3. The frequency is higher.
4. The photon energy is higher.

The refractive indices of water and glass with respect to air are 1.2 and 1.5 respectively. The refractive index of glass with respect to water is

(a) 0.6

(b) 0.8

(c) 1.25

(d) 1.75

The reason for attractive force between two parallel wires in which current is flowing in same direction is:

If the direction of the initial velocity of the charged particle is neither along nor perpendicular to that of the magnetic field, then the orbit will be

(a) A straight line

(b) An ellipse

(c) A circle

(d) A helix