Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Which one of the following properties of an element is not variable?

The SI unit of inductance, the henry, can be written as

(a) Weber/ampere

(b) Volt-second/ampere

(c) Joule/(ampere)2

(d) a, b, c

A wire elongates by 1.0mm when a load W is hung from it. If this wire goes over a a pulley and two weights W each are hung at the two ends, he eloogation of he wire will be:

1. 0.5m
2. 1.0mm
3. 2.0mm
4. 4.0mm.

Assertion  : The number of electrons in a P-type silicon semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature.

Reason      : It is due to law of mass action.

(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.

A cell of e.m.f 1.5 V having a finite internal resistance is connected to a load resistance of 2Ω. For maximum power transfer the internal resistance of the cell should be

(a) 4 ohm

(b) 0.5 ohm

(c) 2 ohm

(d) None of these

When the current through a solenoid increases at a constant rate, the induced current

(a) Is constant and is in the direction of the inducing current

(b) Is a constant and is opposite to the direction of the inducing current

(c) Increases with time and is in the direction of the inducing current

(d) Increases with time and opposite to the direction of the inducing current

If   is 6563 Å, then wave length of second line for Balmer series will be

(a)

(b)

(c)

(d) None of the above

The potential at a point, due to a positive charge of 100μC  at a distance of 9m, is

(a)  V

(b)  V

(c)  V

(d)  V

Two different loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increasing with time. The induced current in the inner loop then, is

(a) Clockwise

(b) Zero

(c) Counter clockwise

(d) In a direction that depends on the ratio of the loop radii

Those substances whose valence band and conduction band are almost in a state of overlap are :