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# WBJEE 2014 Solved Physics Question Paper – Part 12

May 17, 2017 17:49 IST

Find WBJEE 2014 Solved Physics Question Paper – Part 12 in this article. This paper consists of 5 questions (#56 to #60) from WBJEE 2014 Physics paper. Detailed solution of these questions has been provided so that students can match their solutions.

Importance of Previous Years’ Paper:

Previous years’ question papers help aspirants in understanding exam pattern, question format, important topics and assessing preparation. It has also been seen that sometimes questions are repeated in WBJEE Exam. So, this paper will certainly boost your confidence.

56. Find the correct statement(s) about photoelectric effect

(A) There is no significant time delay between the absorption of a suitable radiation and the emission of electrons

(B) Einstein analysis gives a threshold frequency above which no electron can be emitted

(C) The maximum kinetic energy of the emitted photoelectrons is proportional to the frequency of incident radiation

(D) The maximum kinetic energy of electrons does not depend on the intensity of radiation

Ans : (A), (D)

Sol:

Correct statements about photoelectric effect are:

• There is no significant time delay between the absorption of a suitable radiation and the emission of electrons
• The maximum kinetic energy of electrons does not depend on the intensity of radiation

57. A thin rod AB is held horizontally so that it can freely rotate in a vertical plane about the end A as shown in the figure. The potential energy of the rod when it hangs vertically is taken to be zero. The end B of the rod is released from rest from a horizontal position. At the instant the rod makes an angle θ with the horizontal.

58. A stream of electrons and protons are directed towards a narrow slit in a screen (see figure). The intervening region has a uniform electric field E (vertically downwards) and a uniform magnetic field B  (out of the plane of the figure) as shown. Then

(C) neither electrons nor protons will go through the slit irrespective of their speed

(D) electrons will always be deflected upwards irrespective of their speed

Ans: (C), (D)

Sol:

59. A heating element of resistance r is fitted inside an adiabatic cylinder which carries a frictionless piston of mass m and cross-section A as shown in diagram. The cylinder contains one mole of an ideal diatomic gas. The current flows through the element such the temp rapture rises with time t as

(C) the piston moves upwards with constant speed

(D) the piston moves upwards with constant speed

Ans: (A), (C)

Sol:

Internal energy

60. Half of the space between the plates of a parallel-plate capacitor is filled with a dielectric material of dielectric constant K. The remaining half contains air as shown in the figure. The capacitor is now given a charge Q. Then

(A) electric field in the dielectric-filled region is higher than that in the air-filled region

(B) on the two halves of the bottom plate the charge densities are unequal

(C) charge on the half of the top plate above the air-filled part is Q/k+

(D) capacitance of the capacitor shown above is (1 + K)C0/2, where C0 is the capacitance of the same capacitor with dielectric removed

Ans: (B), (C), (D)

Sol:

Also Get:

WBJEE Online Test

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