Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Physics

1. The presence of a large magnetic flux through a coil maintains a current in the coil if the circuit is continuous.
2. A coil of a metal wire kept stationary in a non– uniform magnetic field has an e.m.f induced in it.
3. A charged particle enters a region of uniform magnetic field at an angle of 85° to the magnetic lines of force, the path of the particle is a circle.
4. There is no change in the energy of a charged particle moving in a magnetic field although a magnetic force is acting on it.

Whenever the magnetic flux linked with an electric circuit changes, an emf is induced in the circuit. This is called ______.

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

A current of 4A flows in a coil when connected to a 12V dc source. If the same coil is connected to a 12V, 50 rad/s a.c. source, a current of 2.4A flows in the circuit. Determine the inductance of the coil.

An inductive circuit contains resistance of 10 ohms and an inductance of 2 henry. If an A.C. voltage of 120 Volts and frequency 60 Hz is applied to this circuit, the current would be nearly ______.

Which of the following I-V graph represents ohmic conductors?

Which of the following is correct for V-I graph of a good conductor?

If an electron is moving with velocity `vecnu` produces a magnetic field `vec"B"`, then ______.

The magnetic flux linked with a coil of N turns of area of cross-section A held with its plane parallel to the field B is ______.

Two inductors of inductance L each are connected in series with the opposite? magnetic fluxes. The resultant inductance is ______.

The magnetic flux linked with the coil (in Weber) is given by the equation- Փ = 5t² + 3t + 16. The induced EMF in the coil at time, t = 4 will be ______.

Assertion(A): A proton and an electron, with same momenta, enter in a magnetic field in a direction at right angles to the lines of the force. The radius of the paths followed by them will be same.

Reason (R): Electron has less mass than the proton.

Select the most appropriate answer from the options given below:

Consider a current carrying wire (current I) in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while the current I remain unaffected. The agent that is essentially responsible for is ______.

A metal rod of length 10 cm and a rectangular cross-section of 1 cm × `1/2` cm is connected to a battery across opposite faces. The resistance will be ______.

Two cells of same emf E but internal resistance r₁ and r₂ are connected in series to an external resistor R (Figure). What should be the value of R so that the potential difference across the terminals of the first cell becomes zero.

Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 mm. Conductor B is a hollow tube of outer diameter 2 mm and inner diameter 1 mm. Find the ratio of resistance R_A to R_B.