Atoms — Physics STD 12 Science — Question

The electric potential decreases uniformly from 120V to 80V as one moves on the x-axis from x = -1cm to x = + 1cm. The electric field at the origin.

1. Must be equal to 20Vcm^-1
2. May be equal to 20Vcm^-1
3. May be greater than 20Vcm^-1
4. May be lees than 20Vcm^-1

The phenomenon utilised in an optical fibre is

(a) Refraction	(b) Interference
(c) Polarization	(d) Total internal reflection

The load voltage is approximately constant when a zener diode is:

If the frequency of an A.C is made 4 times of its initial value, the inductive reactance will.

Two nucleons are at a separation of 1 fm. The net force between them is F₁​ if both are neutrons, F₂​ if both are protons, and F₃​ if one is a proton and the other is a neutron then:

While walking on ice, one should take small steps to avoid slipping. This is because smaller steps ensure:

1. Larger friction.
2. Smaller friction.
3. Larger normal force.
4. Smaller normal force.

Five resistors of given values are connected together as shown in the figure. The current in the arm BD will be

(a) Half the current in the arm ABC	(b) Zero
(c) Twice the current in the arm ABC	(d) Four times the current in the arm ABC

There is a current of 20 amperes in a copper wire of  square metre area of cross-section. If the number of free electrons per cubic metre is , then the drift velocity is

(a) 125

(b) 12.5

(c) 1.25

(d) 1.25

A solid that transmits light in visible region and has a very low melting point possesses

(a) Metallic bonding	(b) Ionic bonding
(c) Covalent bonding	(d) Vander Waal’s bonding