PHYSICS BYTES

HP BOARD FINAL QUESTION PAPER 2024

Subject: PHYSICS (Theory) | Class: XII | Series C

Time Allowed: 3 Hours Maximum Marks: 60

GENERAL INSTRUCTIONS:

Candidates are required to give their answers in their own words as far as practicable. Marks allotted to each question are indicated against it.

  • You must write Question Paper Series in the circle at top left side of title page of your Answer-book.
  • While answering your Questions, you must indicate on your Answer-book the same Question No. as appears in your Question Paper.
  • Do not leave blank page/pages in your Answer-book.
  • The question paper has 29 questions. All the questions are compulsory. The Internal choice is given where applicable.
  • Answers should be brief and to the point.
  • Question Nos. 1 to 12 are MCQ carrying 1 mark each.
  • Question Nos. 13 to 18 are very short answer type questions carrying 2 marks each.
  • Question Nos. 19 to 26 are short answer type questions carrying 3 marks each and Question Nos. 27 to 29 carry 4 marks each.
  • There is no negative marking.

SECTION - A

(1 Mark Each)

1.
The SI unit of electric dipole moment is :
(a) Cm
(b) C
(c) $Cm^{-1}$
(d) $Nm^{-1}$
[1]
2.
If a charge flowing through a cross section of a wire can be given as $q=5t^{2}+8t$ (where 'q' is charge and 't' is time), then calculate the Electric current at $t=2s$.
(a) 20 A
(b) 36 A
(c) 13 A
(d) 28 A
[1]
3.
A charged particle enters in a magnetic field with some velocity parallel to the magnetic field. The nature of path followed by the charged particle will be :
(a) helical
(b) circular
(c) straight line
(d) parabolic
[1]
4.
The output of a step down transformer is measured to be 24 V when connected to a 12 watt light bulb. The value of the peak current is :
(a) $\frac{1}{\sqrt{2}} A$
(b) $\sqrt{2} A$
(c) 2 A
(d) $2\sqrt{2} A$
[1]
5.
Electromagnetic waves are produced by :
(a) static charge
(b) chargeless particles
(c) accelerating charge
(d) None of these
[1]
6.
A passenger in an Aeroplane shall :
(a) never see a rainbow
(b) may see a primary and a secondary rainbow as concentric circles
(c) may see a primary and a secondary rainbow as concentric arcs
(d) shall never see a secondary rainbow
[1]
7.
Momentum of a photon of frequency $\nu$ is:
(a) $\frac{h\nu}{c}$
(b) $h\nu c$
(c) $\frac{h}{\nu c}$
(d) $\frac{hc}{\nu}$
[1]
8.
The binding energy per nucleon is maximum in :
(a) ${}_{2}^{4}He$
(b) ${}_{26}^{56}Fe$
(c) ${}_{56}^{141}Ba$
(d) ${}_{92}^{235}U$
[1]
9.
The relation between base current $(I_{b})$, emitter current $(I_{e})$ and collector current $(I_{c})$ for common-emitter transistor is :
(a) $I_{b}=I_{e}+I_{c}$
(b) $I_{c}=I_{b}+I_{e}$
(c) $I_{e}=I_{b}+I_{c}$
(d) None of these
[1]
10.
Attenuation in optical fibre is mainly due to:
(a) scattering
(b) absorption and scattering
(c) dispersion
(d) None of these
[1]
11.
Peacock and other birds shows multi-colour due to :
(a) Reflection of light
(b) Refraction of light
(c) Interference of light
(d) Polarisation of light
[1]
12.
Radius of curvature of plane mirror is:
(a) Zero
(b) Infinite
(c) One
(d) None of these
[1]

SECTION - B

(2 Marks Each)

13.
Explain why two electric field lines never cross each other at a point?
[2]
14.
Why capacitor blocks d.c. ? Explain.
[2]
15.
Show that the average energy density of the Electric field is equal to the average energy density of the magnetic field.
OR
A radio wave can tune into any station in the 7.5 MHz to 12 MHz band. What is the corresponding wavelength band?
[2]
16.
Derive Einstein's photoelectric equation.
[2]
17.
Give the Logic symbol, truth table and Boolean expression of NOR gate.
OR
What is p-n junction diode? Draw the complete characteristic of a junction diode.
[2]
18.
What is total internal reflection? Under what conditions does it take place?
OR
Why the colour of sky is blue? Explain.
[2]

SECTION - C

(3 Marks Each)

19.
Obtain an expression for internal resistance of a cell by using potentiometer.
[3]
20.
Define S.I. unit of Electric energy. A heating element of resistance 25Ω is connected to 220 V supply. How much heat will be produced in one minute.
[3]
21.
State and prove Ampere's circuital law.
OR
Derive an expression for potential energy of a bar magnet; when placed in uniform magnetic filed? When it is maximum and minimum.
[3]
22.
Derive an expression for the maximum force experienced by a straight conductor of length 'l', carrying current 'I' and kept in a uniform magnetic field 'B'.
[3]
23.
Prove that for diffraction at a single slit, width of central maximum is twice as that of secondary maximum.
[3]
24.
Explain the laws of Radioactive decay.
OR
Obtain binding energy (in MeV) and binding energy per nucleon of a nitrogen nucleus given mass of ${}_{7}^{14}N=14.00307$ amu, mass of proton $=1.007825$ amu and mass of neutron $=1.008665$ amu.
[3]
25.
Explain transistor (NPN) as an amplifier using circuit diagram.
OR
What is a Zener diode? Explain, how it is used as a Voltage regulator ?
[3]
26.
What is Communication system? Give the block diagram of Communication system.
[3]

SECTION - D

(4 Marks Each)

27.
Define the Electric potential. Obtain an expression for it, due to a point charge 'q' at a point 'P' at a distance 'r' from 'q'.
OR
State Coulomb's law in Electrostatics. Give its vector form. Calculate Coulomb's force between two $\alpha$-particles separated by a distance of $3.2\times10^{-15}$ m.
[4]
28.
Describe the principle, construction and theory of transformer.
[4]
29.
Derive an expression for the conditions of constructive and destructive interference in Young's double slit experiment.
OR
State and prove Brewster's law. Show that at polarising angle, the reflected and refracted beams of light are at 90° to each other.
[4]
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