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

Obtain if the circuit is connected to a 110 V, 12 kHz supply? Hence, explain the statement that a capacitor is a conductor at very high frequencies. Compare this behaviour with that of a capacitor in a dc circuit after the steady state.

An applied voltage signal consists of a superposition of a dc voltage and an ac voltage of high frequency. The circuit consists of an inductor and a capacitor in series. Show that the dc signal will appear across C and the ac signal across L.

Alternating current is so called because _______.

In a circuit containing resistance only, voltage and current are ______.

Average power supplied to an inductor over one complete cycle is ______.

If circuit containing inductance only, the current ______.

Photoelectric effect is possible ______.

What is the unit of mass when measured on the atomic scale?

In a pure or intrinsic semiconductor, valence band holes and conduction-band electrons are always ______.

A charged particle moves through a magnetic field perpendicular to its direction. Then ______.

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 ______.