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

The amplification factor of a triode operating in the linear region depends strongly on ____________ .

(i) Write the truth tables of the logic gates marked P and Q in the given circuit.
(ii) Write the truth table for the circuit. 

Why are NOR gates considered as universal gates?

The outputs of two NOT gates are fed to a NOR gate. Draw the logic circuit of the combination of gates. Write its truth table. Identify the gate equivalent to this circuit.

You are given circuit as shown in the figure, which consists of NAND gate. Identify the logic operation carried out by the two. Write the truth table. Identify the gates equivalent to the tow circuits.

You are given a circuit as shown in the figure, which consists of the NAND gate. Identify the logic operation carried out by the two. Write the truth table. Identify the gates equivalent to the tow circuit.

A toroid has a core (non-ferromagnetic) of inner radius 25 cm and outer radius 26 cm, around which 3500 turns of a wire are wound. If the current in the wire is 11 A, what is the magnetic field (a) outside the toroid, (b) inside the core of the toroid, and (c) in the empty space surrounded by the toroid?

A capacitor has some dielectric between its plates, and the capacitor is connected to a dc source. The battery is now disconnected and then the dielectric is removed, then ______.

A current carrying loop is placed in a uniform magnetic field in four different orientations as shown in the figure. Arrange them in the decreasing order of potential energy.

(1)	(2)	(3)	(4)

Two wires of the same length are shaped into a square of side 'a' and a circle with radius 'r'. If they carry same current, the ratio of their magnetic moment is ______.

A parallel plate capacitor is made of two dielectric blocks in series. One of the blocks has thickness d₁ and dielectric constant k₁ and the other has thickness d₂ and dielectric constant k₂ as shown in figure. This arrangement can be thought as a dielectric slab of thickness d (= d₁ + d₂) and effective dielectric constant k. The k is ______.

A capacitor is made of two circular plates of radius R each, separated by a distance d << R. The capacitor is connected to a constant voltage. A thin conducting disc of radius r<<R and thickness t << r is placed at a centre of the bottom plate. Find the minimum voltage required to lift the disc if the mass of the disc is m.

Truth table for the given circuit (Figure) is ______.

Two car garages have a common gate which needs to open automatically when a car enters either of the garages or cars enter both. Devise a circuit that resembles this situation using diodes for this situation.

How would you set up a circuit to obtain NOT gate using a transistor?

Write the truth table for the circuit shown in figure. Name the gate that the circuit resembles.

Draw the output signals C₁ and C₂ in the given combination of gates (Figure).

An X-OR gate has following truth table:

It is represented by following logic relation `Y = barA.B + A.barB`. Build this gate using AND, OR and NOT gates.

Write the functions of three segments of a transistor.

For a CE-transistor amplifier, the audio signal voltage across the collector resistance of 2 kΩ is 2 V. Suppose the current amplification factor of the transistor is 100, find the input signal voltage and base current if the base resistance is 1 kΩ.