CBSE Class 12 Physics Paper 2018 (page 1)

CBSE Class 12 Physics Paper 2018

Page 1

{ With a few Sample Solutions }

Q.1) [marks=1]: A Proton and electron travelling along parallel paths enter a region of uniform magnetic field acting perpendicular to their paths. Which of them would move in a circular path with higher frequency?

Answer: In a situation like this, we know that the frequency of revolution is given by the equation: f = qB/m

Since  the magnitude of the charge of a proton and an electron are the same, therefore frequency varies inversely with mass. As the electron has lower mass, so its frequency will be higher.

Q.2)[marks=1]: Name the electromagnetic radiations used for

(a) water purification and (b) eye surgery.

Answer: (a) ultraviolet rays

(b) infrared rays.

Q.3)[marks=1]: Draw graphs showing variation of photoelectric current with applied voltage for two incident radiations of equal frequency and different intensities.  Mark the graph for the radiation of higher intensity.

Answer: [Graph to be inserted.]

Q.4)[marks=1]: Four nuclei of an element undergo fusion to form a heavier nucleus, with release of energy. Which of the two -the parent or the daughter nucleus - would have higher binding energy per nucleon?

Answer: In a fusion reaction, energy is released. So, the daughter nucleus will have higher binding energy per nucleon.

Q.5)[marks=1]: Which mode of propagation is used by shortwave broadcast services?

Answer: Sky wave mode of propagation is used by shortwave broadcast services.


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