Magnetism And Matter — Physics STD 12 Science — Question

Two charges of 10C and -15C are separated in air by 1m.The ratio of force exerted by one on the other is:

Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?

In a metal, the separation between conduction band and valence band is of the order:

During a nuclear fission reaction:

1. A heavy nucleus breaks into two fragments by itself a light nucleus bombarded by thermal neutrons breaks up.
2. A light nucleus bombarded by thermal neutrons breaks up.
3. A heavy nucleus bombarded by thermal neutrons breaks up.
4. Two light nuclei combine to give a heavier nucleus and possible other products.

Between the plates of a parallel plate capacitor a dielectric plate is introduced just to fill the space between the plates. The capacitor is charged and later disconnected from the battery. The dielectric plate is slowly drawn out of the capacitor parallel to the plates. The plot of the potential difference across the plates and the length of the dielectric plate drawn out is

(a)

(b)

(c)

(d)

Assertion   :  The resistance of super-conductor is zero.

Reason      : The super-conductors are used for the transmission of electric power.

(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.

Frequency and potential difference of AC sent to homes in India is:

In the circuit shown in the adjoining figure, the current between B and D is zero, the unknown resistance is of

(a) 4 Ω

(b) 2 Ω

(c) 3 Ω

(d) em.f. of a cell is required to find the value of X

The mass number of a nucleus is: