ISC (Science) ISC Class 12 - CISCE Question Bank Solutions for Physics (Theory)

Assertion: When an electric current is passed through a moving coil galvanometer, its coil gets deflected.

Reason: A circular coil produces a uniform magnetic field around itself when an electric current is passed through it.

The figure below shows a circuit containing an ammeter A, a galvanometer G and a plug key K. When the key is closed:

A galvanometer of resistance 100 Ω gives a full-scale deflection for a potential difference of 200 mV.

1. What must be the resistance connected to convert the galvanometer into an ammeter of the range 0-200 mA?
2. Determine resistance of the ammeter.

 A closed surface in vacuum encloses charges –q and +3q. The total electric flux emerging out of the surface is :

Define equipotential surface. 

A rectangular loop of area 5m2, has 50 turns and carries a current of 1A. It is hold in a uniform magnetic field of 0.1T, at an angle of 30°. Calculate the torque experienced by the coil. 

State Gauss’ Law.

What is meant by an equipotential surface?

Deduce an expression for equivalent capacitance C when three capacitors C₁, C₂ and C₃ connected in parallel.

Figure 4 below shows a capacitor C, an inductor L and a resistor R, connected in series
to an a.c. supply of 220 V

Calculate:

1) The resonant frequency of the given CLR circuit.

2) Current flowing through·the circuit.

3) Average power consumed by the circuit.

Three capacitors of capacitance `C_1 = 3muf` , `C_2 = 6muf` , `C_3 = 10muf` , are connected to a 10V battery as shown in figure 3 below : 

Calculate :

(a) Equivalent capacitance.

(b) Electrostatic potential energy stored in the system 

A wire of resistance ‘R’ is cut into ‘n’ equal parts. These parts are then connected in parallel with each other. The equivalent resistance of the combination is: 

ε₁ and ε₂ are two batteries having emf of 34V and 10V respectively and internal resistance of 1Ω and 2Ω respectively. They are connected as shown in the figure below. Using Kirchhoff’s Laws of electrical networks, calculate the currents I₁ and I₂.

On which conservation principle is Kirchoff's Second Law of electrical networks based?

In the circuit shown in the figure below, E₁ and E₂ are two cells having emfs 2 V and 3 V respectively, and negligible internal resistance. Applying Kirchhoff’s laws of electrical networks, find the values of currents l₁ and I₂.

In the circuit shown in Figure below, E₁ and E₂ are batteries having emfs of 25V and 26V. They have an internal resistance of 1 Ω and 5 Ω respectively. Applying Kirchhoff’s laws of electrical networks, calculate the currents I₁ and I₂.

What is meant by the statement: "Relative permittivity of water is 81"?

The figure below shows two batteries, E1 and E2, having emfs of 18V and 10V and internal resistances of 1 Ω and 2 Ω, respectively. W₁, W₂ and W₃ are uniform metallic wires AC, FD and BE having resistances of 8 Ω, 6 Ω and 10 Ω respectively. B and E are midpoints of the wires W₁ and W₂. Using Kirchhoff's laws of electrical circuits, calculate the current flowing in the wire W₃:

Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.

An electrical bulb is marked 200V, 100W. Calculate the electrical resistance of its filament. If five such
bulbs are connected in series to a 200V supply, how much current will flow through them?