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

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West Bengal Board Model Questions & Answers : Class-10

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