Subject

Physics

Class

ICSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

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 Multiple Choice QuestionsLong Answer Type

21.

a) Two point charges Q1 = 400 μC and Q2 = 100 straight mu space straight C are kept fixed, 60 cm apart in vacuum.Find intensity of the electric field at midpoint of the line joining Q1 and Q2.
b) i) State Gauss' law.

ii) In an electric dipole, at which point is the electrical potential zero?


22.

a) Obtain an expression for equivalent capacitance when three capacitors C1, C2 and C3 are connected in series.

b) A metallic wire has a resistance of 3.0 ohm and 0o Cand 4.8 ohm at 150o C. Find the temperature coefficient of resistance of its material?


23. a) In the circuit shown in figure E1 and E2 are two cells having emfs 2 V and 3 V respectively, and negligible internal resistances. Applying Kirchoff's laws of electrical networks, find the values of currents I1 and I2.
 
b) State how a moving coil galvanometer can be converted into an ammeter.

24.

a) Draw a labelled circuit diagram of a potentiometer to measure internal resistance of a cell. Write the working formula.

b) i) Define Curie temperature.
ii) If magnetic susceptibility of a certain magnetic material is 0.0001, find its relative permeability.


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 Multiple Choice QuestionsShort Answer Type

25.

i) Two infinitely long current carrying conductors X and Y are kept parallel to each other, 24 cm apart in vacuum. They carry currents of 5 A and 7 A respectively, in the same direction, as shown in the figure below. Find the position os a neutral point, i.e., a point where resultant magnetic flux density is zero.



ii) If current through the conductor Y is reversed in direction, will neutral point lie between x and Y, to the left of X or to the left of Y?


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26.

i) Define Ampere in terms of force between two current carrying conductors.

ii) What is an ideal transformer.


i) Ampere is defined as the amount of electrical current required to maintain a force 2x10-7 newton per metre between two infinitely long parallel wires of negligible cross-section held one metre apart in vacuum.

ii) For an ideal transformer, there is no energy loss, the output power will be equal to the input power.

That is,

Pout = Pin

Vs is = VP ip

rightwards double arrowstraight V subscript straight S over straight V subscript straight P equals i subscript p over i subscript s


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 Multiple Choice QuestionsLong Answer Type

27.

a) A coil having self-inductance of 0.7 H and resistance of 165 ohm is connected to an ac source of 275 V, 50 Hz. If straight pi space equals space 22 over 7.
Calculate:

i) reactance of the coil
ii) impedance of the coil
iii) current flowing through the coil

b) Draw a labelled graph showing variation of impedance of a series LCR circuit with frequency of the a.c. supply.


28.

a) Derive Snell's law of refraction using Huygen's wave theory.

b) Monochromatic light of wavelength 650 nm falls normally on a slit of width 1.3 x 10-4 and the resulting Fraunhofer diffraction is obtained on a screen. Find the angular width of the central maxima.


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29.

a) In Young's Double Slit experiment, show that:

straight beta space equals space λD over straight d, where the terms have their usual meaning.
b) A ray of ordinary light is travelling in air. It is incident on air-glass pair at a polarising angle of 56o. Find the angle of refraction in glass.


30. a) Find the angle of incidence at which a ray of monochromatic light should be incident on the first surface AB of a regular glass prism ABC so that the emergent ray grazes the adjacent surface AC. (Refractive index of glass = 1.56)

b) State how focal length of glass lens (refractive index 1.5) changes when it is completely immersed in:
i) Water (Refractive Index 1.33)
ii) A liquid (Refractive index 1.65)

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