CBSE Class 12 Physics Term 2 Exam 2022: Check the Answer key to a few questions that were regarded as difficult by the students of CBSE Class 12th. Check the question paper and solution below.
CBSE Class 12 Physics Exam Term 2 was conducted today that is on May 20, 2022 across the country. Thousands of students attempted the exam and seemed satisfied with the paper. The exam was labeled as a moderately difficult one by the students today.
The students can find the solutions to a few questions listed below which were found to be tough by many students. Check the following reviews below.
CBSE Class 12 Physics Term 2 Paper Analysis: ‘Not Easy’, Say Students- Check Expert Review | Answer Key To Be Available Soon
CBSE Class 12 Physics Term 2 Question Paper 2022: FREE DOWNLOAD
CBSE Class 12 Physics Term 2 Answer Key: Check Questions and Solutions
Take a look at the following solutions to the questions below.
Q. Two crystals c1 and c2, made of pure silicon, are doped with arsenic and aluminum respectively
Identify the extrinsic semiconductors so formed
C1 – n-type semiconductor
C2 – p-type semiconductor
why is doping of intrinsic semiconductors necessary
Answer: Doping of intrinsic semiconductors is done to increase the concentration of the majority charge carrier so that it can be used as a p-type or n-type semiconductor in the diode.
Q. Why is a photo-diode operated in reverse bias whereas the current in the forward bias is much larger than that in the reverse bias? Explain.
Ans. A photodiode converts incident light to electric current more effectively in reverse bias conditions. Actually, in a forward bias, the depletion region between the PN junction is very thin because it allows current to flow. But in reverse bias the depletion region becomes thick. Now, The incident light creates electron-hole pairs in the depletion region. Greater the area of depletion region, more are the electron-hole pairs that can be created by the incident light which is directly proportional to the amount of current produced. That’s why photodiode is connected in reverse bias.
Q. (a) What results do you expect if the alpha particle scattering experiment is repeated using a thin sheet of hydrogen in place of a gold foil? Explain. (Hydrogen is a solid at temperatures below 14 K.)
Ans: In the alpha-particle scattering experiment, if a thin sheet of solid hydrogen is used in place of a gold foil, then the scattering angle would not be large enough. This is because the mass of hydrogen (1.67 × 10 −27 kg) is less than the mass of incident α − particles (6.64 × 10 −27 kg). Thus, the mass of the scattering particle is more than the target nucleus (hydrogen). As a result, the α − particles would not bounce back if solid hydrogen is used in the α-particle scattering experiment.
Q. How will the interference pattern in Young’s double-slit experiment be affected if:
i) The screen is moved away from the plane of the slits
Ans. When the screen is moved away, ‘D’ increases, therefore the width of the fringes increases.
ii) The source slit is moved away from the plane of the slits
Ans. As the source slit width increases, the fringe pattern gets less and less sharp. When the source slit is so wide then the interference pattern disappears.
iii) The phase difference between the light waves emanating from the two slits S1 and S2 changes from 0 to π and remains constant
Ans. The central fringe will become dark, as the phase difference between the light waves from two slits is odd after changing to π
Q. Define the SI unit of power of the lens
Ans. The power of a lens is its ability to converge or diverge the rays of light falling on it. The power of a lens is equal to the reciprocal of the focal length of the lens.SI unit of power is dioptre (D).
P = f1 = 1D. The power of the lens is the ability of a lens to converge the rays falling on it. One dioptre is the power of the lens whose focal length is 1m.
Q. A Plano-convex lens is made of glass with a refractive index of 1.5. The radius of curvature of the convex surface is 25cm.
Calculate the focal length of the lens.
u = 1.5
The radius of curvature of the plane surface is infinity ie R1 = ∞
The radius of curvature of convex surface R2 = −25 cm
1 / f = (u-1) (1 / R1- 1 / R2)
Q. Arrange the following electromagnetic radiation in the ascending order of their frequencies
X Rays, Microwaves, Gamma rays, radio waves
ii) Write any two uses of these radiations.
Ans. X rays can be used in Medical Science, Security purposes, Astronomy etc. Infrared rays find use in Electrical heaters, cooking food etc like microwaves.
The other questions would soon be provided here with their solutions. Keep refreshing the page for the same.
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