Subject

Physics

Class

CBSE 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 QuestionsShort Answer Type

11.

State the underlying principle of a cyclotron. Write briefly how this machine is used to accelerate charged particles to high energies.

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12.

An electric dipole of length 4 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of 4  Nm. Calculate the potential energy of the dipole, if it has charge ±8 n C. 

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13.

A potentiometer wire of length 1 m has a resistance of 10 Ω. It is connected to a 6 V battery in series with a resistance of 5 Ω. Determine the emf of the primary cell which gives a balance point at 40 cm. 

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14.

(a) Obtain the expression for the energy stored per unit volume in a charged parallel plate capacitor.

(b) The electric field inside a parallel plate capacitor is E. Find the amount of work done in moving a charge q over a closed loop a b c d a. 


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15.

(a) State Ampere's circuital law, expressing it in the integral form.

(b) Two long coaxial insulated solenoids, S1 and S2 of equal lengths are wound one over the other as shown in the figure. A steady current 'I' flow thought the inner solenoid S1 to the other end B, which is connected to the outer solenoid S2 through which the same current 'I' flows in the opposite direction so as to come out at end A. If n1 and n2 are the number of turns per unit length, find the magnitude and direction of the net magnetic field at a point

(i) Inside on the axis, and
(ii) outside the combined system.        

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16.

Answer the following:

(a) Name the EM waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.

(b) If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.

(c) An EM wave exerts pressure on the surface on which it is incident. Justify.
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17.

A convex lens is placed in contact with a plane mirror. A point object at a distance of 20 cm on the axis of this combination has its image coinciding with itself. What is the focal length of the lens? 


Given, convex lens placed in contact with a plane mirror.

Image of the object coincides with the object.

So, the rays refracted from the first lens and then reflected by the plane mirror will be retracing their path.  This would happen when rays refracted by the convex lens fall normally on the mirror i.e., the refracted rays form a beam parallel to principal axis of the lens.

Hence, the object is at the focus of the convex lens.

Therefore, focal length, f = 20 cm

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18.

The figure given below shows the block diagram of a generalized communication system. Identify the element labelled 'X' and write its function.


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19.

For a single slit of width "a", the first minimum of the interference pattern of a monochromatic light of wavelength λ occurs at an angle of lambda over a . At the same angle of lambda over a  , we get a maximum for two narrow slits separated by a distance "a". Explain. 

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20.

Write the truth table for the combination of the gates shown. Name the gates used. 

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