West Bengal Board Model Questions & Answers : Class-12 Physics

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Exam Name :West Bengal Board Model Questions & Answers

Subject : Physics (Model Paper's I,II,III & IV)

Class : 12

Model Question Physics − 3

Kanak Ranjan Tola

Ballygunj Govt. High School

Group A

Give answers to the following questions either in      one word    or one sentence.

(Alternatives are to be noted):                                                                         1 x 10 = 10

1.(a)    ‘A progressive wave carries energy in a plane perpendicular to the  plane of wave front’ −− is the statement true

Ans:    The statement is not true.

(b)       Beats will be audible if the difference in frequencies  of two superposing waves is not greater than.........                                                           1

Ans:    Beats will be audible if the difference in frequencies  of two superposing waves is not greater than     15     .

(c)       The value of potential inside a hollow spherical conductor is ......................  1

Ans:    The  value  of  potential inside  a  hollow  spherical conductor  is

 R= radius of the conductor. (d) Can it be possible to accelerate a neutron in a cyclotron accelerator ? 1 Ans.   (e) It is not possible to accelerate a neutron in cyclotron accelerator.   Comment whether P−type semiconductor is positively charged or not ? 1 Ans.   (f) P−type semiconductor is not charged.   Give an example where electron ejects photon. 1 Ans. In X−ray production electron ejects photon.

Group B

2. (a)   Why centrifugal force is termed as pseudo force ?                                       2

Ans.    There is no existence of centrifugal force in an inertial frame of reference. The source of this force in a noninertial frame, cannot be find out.             It appears not due to action−reaction like seal force. So it is termed as pseudo force.

(b)        Degree of freedom of molecules of a gas is 5. Find the value of Cp  / Cv