Science (English Medium) Class 12 - CBSE Question Bank Solutions for Physics

The total flux through the faces of the cube with side of length a if a charge q is placed at corner A of the cube is ______.

The SI unit of electric flux is ______.

Ampere’s circuital law is given by _______.

Two identical current carrying coaxial loops, carry current I in opposite sense. A simple amperian loop passes through both of them once. Calling the loop as C, then which statement is correct?

A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by ______.

An electric charge q is placed at the centre of a cube of side a. The electric flux on one of its faces will be ______.

Total electric flux coming out of a unit positive charge kept in air is ______.

The electric field intensity due to an infinite cylinder of radius R and having charge q per unit length at a distance rir r(r > R) from its axis is ______.

A point charge q is placed at a distance a/2 directly above the centre of a square of side a. The electric flux through the square is ______.

By increasing the temperature, the specific resistance of a conductor and a semiconductor -

An air-cored solenoid with length 30 cm, area of cross-section 25 cm2 and number of turns 800, carries a current of 2.5 A. The current is suddenly switched off in a brief time of 10^-3s. Ignoring the variation in magnetic field near the ends of the solenoid, the average back emf induced across the ends of the open switch in the circuit would be ______.

If both the number of turns and core length of an inductor is doubled keeping other factors constant, then its self-inductance will be ______.

You are riding in an automobile of mass 3000 kg. Assuming that you are examining the oscillation characteristics of its suspension system. The suspension sags 15 cm when the entire automobile is placed on it. Also, the amplitude of oscillation decreases by 50% during one complete oscillation. Estimate the values of the spring constant k.

Draw the circuit diagram of a full wave rectifier.

Explain with a proper diagram how an ac signal can be converted into dc (pulsating) signal with output frequency as double than the input frequency using pn junction diode. Give its input and output waveforms.

What will be the total flux through the faces of the cube (figure) with side of length a if a charge q is placed at

1. A: a corner of the cube.
2. B: mid-point of an edge of the cube.
3. C: centre of a face of the cube.
4. D: mid-point of B and C.

Temperature dependence of resistivity ρ(T) of semiconductors, insulators and metals is significantly based on the following factors:

1. number of charge carriers can change with temperature T.
2. time interval between two successive collisions can depend on T.
3. length of material can be a function of T.
4. mass of carriers is a function of T.

Two identical current carrying coaxial loops, carry current I in an opposite sense. A simple amperian loop passes through both of them once. Calling the loop as C ______.

1. `oint B.dl = +- 2μ_0I`
2. the value of `oint B.dl` is independent of sense of C.
3. there may be a point on C where B and dl are perpendicular.
4. B vanishes everywhere on C.

The self inductance L of a solenoid of length l and area of cross-section A, with a fixed number of turns N increases as ______.

Consider an infinitely long wire carrying a current I(t), with `(dI)/(dt) = λ` = constant. Find the current produced in the rectangular loop of wire ABCD if its resistance is R (Figure).