Nuclei — Physics STD 12 Science — Question

A coil of self inductance 50 henry is joined to the terminals of a battery of e.m.f. 2 volts through a resistance of 10 ohm and a steady current is flowing through the circuit. If the battery is now disconnected, the time in which the current will decay to 1/e of its steady value is

(a) 500 seconds

(b) 50 seconds

(c) 5 seconds

(d) 0.5 seconds

Consider a sample of a pure beta-active material:

1. All the beta particles emitted have the same energy.
2. The beta particles originally exist inside the nucleus and are ejected at the time of beta decay.
3. The antineutrino emitted in a beta decay has zero mass and hence zero momentum.
4. The active nucleus changes to one of its isobars after the beta decay.

In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will

(a) Increase

(b) Decrease

(c) Remain constant

(d) None of these

A silver voltameter of resistance 2 ohm and a 3 ohm resistor are connected in series across a cell. If a resistance of 2 ohm is connected in parallel with the voltameter, then the rate of deposition of silver

(a) Decreases by 25%	(b) Increases by 25%
(c) Increases by 37.5%	(d) Decreases by 37.5%

A magnetic field can be produced by:

 The opposition offered by the electrolyte of the cell to the flow of current through itself is known as __________.

In the given reaction  Radioactive radiations are emitted in the sequence

(a) α, β,γ

(b) β ,α, γ

(c) γ ,α, β

(d) β , γ ,α

The x-component of the resultant of several vectors:

1. Is equal to the sum of the x-components of the vectors.
2. May be smaller than the sum of the magnitudes of the vectors.
3. May be greater than the sum of the magnitudes of the vectors.
4. May be equal to the sum of the magnitudes of the vectors.