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

When current flowing through a solenoid decreases from 5A to 0 in 20 milliseconds, an emf of 500V is induced in it.

1. What is this phenomenon called?
2. Calculate coefficient of self-inductance of the solenoid.

In a potentiometer experiment, balancing length is found to be 120 cm for a cell E₁ of emf 2V. What will be the balancing length for another cell E₂ of emf 1.5V? (No other changes are made in the experiment.)

Define critical angle for a given medium.

In a potentiometer experiment, the balancing length with a resistance of 2Ω is found to be 100 cm, while that of an unknown resistance is 500 cm. Calculate the value of the unknown resistance. 

Draw a labelled circuit diagram of a potentiometer to measure the internal resistance ‘r’ of a cell. Write the working formula (derivation is not required). 

Figure below shows two resistors R₁ and R₂ connected to a battery having an emf of 40V and negligible internal resistance. A voltmeter having a resistance of. 300 Ω is used to measure the potential difference across R₁ Find the reading of the voltmeter.

Draw a labelled circuit diagram of a potentiometer to compare emfs of two cells. Write the working formula (Derivation not required).

Name the principle on the basis of which optical fibres work.

Name any two phenomena which take place in the formation of a rainbow.

Three identical cells each of emf 'e' are connected in parallel to form a battery. What is the emf of the battery?

The Figure below shows a potentiometer circuit in which the driver cell D has an emf of 6 V and internal resistance of 2 Ω. The potentiometer wire AB is 10 m long and has a resistance of 28 Ω. The series resistance R_S is of 2 Ω.

1. The current I_p flowing in the potentiometer wire AB when the jockey (J) does not touch the wire AB.
2. emf of the cell X if the balancing length AC is 4.5 m.

In a potentiometer, a cell is balanced against 110 cm when the circuit is open. A cell is balanced at 100 cm when short-circuited through a resistance of 10 Ω. Find the internal resistance of the cell.

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: 

The intensity of the electric field at a point at a perpendicular distance ‘r’ from an infinite line charge, having linear charge density ‘λ’ is given by:

A charged oil drop weighing 1.6 x 10^-15 N is found to remain suspended in a uniform electric field of intensity 2 x 10³ Nc^-1. Find the charge on the drop. 

The focal length of a concave lens is 20 cm. The focal length of a convex lens is 25 cm. These two are placed in contact with each other. What is the power of the combination? Is it diverging, converging or undeviating in nature?

In case of an infinite line charge, how does intensity of electric field at a point change, if at all, when.

1. charge on it is doubled?
2. distance of the point is halved?