PSEB 12th Sample Paper 2027 Physics

FOR PUNJAB CLASS 12 PREPARATION

PSEB 12th Sample
Paper 2027 Physics
EXAM YEAR TYPE SUBJECT

Punjab Class 12 2027 Sample Paper Physics

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m .co s e m PSEB 12th Sample Paper 2027 Physics

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PSEB 12th Physics Question Paper
Section A: 1 Mark Questions (Objective)
1. The direction of dipole moment of an electric dipole is always from
(a) negative to positive charge
(b) positive to negative charge
(c) along the perpendicular bisector of the dipole
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(d) electric dipole moment is a scalar quantity. It has no direction.
[Knowledge, below average]
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2. Why do the electrostatic field lines not form closed loops?
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(a) Because electrostatic field is a non-conservative field

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(b) Because electrostatic field is a conservative field
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(c) Because electrostatic field lines do not cross each other
(d) Because electrostatic field lines are always perpendicular to the charged surface
[Understanding, below average]
3. The resistivity of a wire
(a) increases with the length of the wire
(b) decreases with the area of cross-section
(c) decreases with the length and increases with the cross-section of wire
(d) none of the above statement is correct
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[Knowledge, average]
4. Lenz’s law gives
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(a) magnitude of induced emf/current
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(b) direction of induced emf/current
(c) both magnitude and direction of induced emf/current
(d) neither magnitude nor direction of induced emf/current
[Knowledge, below average]
5. The variation of instantaneous current I(t) and instantaneous
emf E(t) in a circuit is as shown in the figure given below.
Which of the following statements is correct?
(a) The voltage lags behind the current by π/2
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(b) The voltage leads the current by π/2
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(c) The voltage and the current are in phase
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(d) The voltage leads the current by π
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las [Analysis, below average]
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6. Why are microwaves considered suitable for RADAR
a systems used in aircraft navigation?
(a) On account of larger wavelength than radiowaves, they can bend around the corners of obstacles.
(b) On account of larger wavelength than radiowaves, they can be sent as beam signals.
(c) On account of smaller wavelength than radiowaves, they can bend around the corners of obstacles.
(d) On account of smaller wavelength than radiowaves, they can be sent as beam signals.
[Understanding, average]

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PSEB 12th Sample Paper 2027 Physics

7. How does the focal length of a lens change when red light incident on it is replaced by violet light?
(a) increases
(b) remains same
(c) decreases
(d) may increase or decrease
[Understanding, below average]
8. In the diffraction pattern obtained in the case of a single slit, on making slit width double, the width of
central maximum
(a) gets doubled
(b) becomes half
(c) remains same
(d) becomes 4 times
[understanding, below average]
9. Two thin lenses of power +10 D and -5 D are placed in contact. The focal length of the combination of
two lenses is
(a) 5 cm (b) 10 cm (c) 15 cm (d) 20 cm
[Application average]
10. Discriminate between the intensity vs wavelength curve in case of interference and diffraction
phenomenon.
(a) In interference, maximum intensity of all the fringes is same and in case of diffraction, maximum
intensity decreases with increase in path difference.
(b) In diffraction, maximum intensity of all the fringes is same and in case of interference, maximum
intensity decreases with increase in path difference.
(c) In interference as well as diffraction, the maximum intensity of all the fringes remains same.
(d) In interference the intensity of dark fringe may never become zero and the contrast is very poor but in
diffraction, the intensity of dark fringe becomes zero and the contrast is very good.
[Analysis, average]
11. According to Einstein photoelectric equation, the graph between the kinetic energy of photoelectrons
ejected and the frequency of incident radiation is

[Analysis, average]
12. Four nuclei of an element undergo fusion to form a heavier nucleus, with release of energy. Which of
the two parent or daughter nucleus would have higher binding energy per nucleon?
(a) parent nucleus

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m .co s e m PSEB 12th Sample Paper 2027 Physics

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a (b) daughter nucleus ag
(c) both have same binding energy
(d) any of the two may have higher binding energy
[Understanding, average]
13. Two stable isotopes 3Li6 and 3Li7 have respective abundances of 7.7% and 92.5%. These isotopes have
masses 6.01512 u and 7.01600 u respectively. The atomic weight of lithium is
(a) 6.941 u
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(b) 6.321 u
(c) 6.561 u
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(d) 6.621 u
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[Application, above average]
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14. The diagram shows the energy levels for an electron in a certain
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atom. Which transition shown represents the emission of a photon
with the most energy?
(a) I (b) II (c) III (d) IV
[Analysis, average]
15. The dominant mechanism for motion of charge carriers in
forward and reverse biased silicon PN junction are
(a) drift in forward biased, diffusion in reverse biased
(b) diffusion in forward biased, drift in reverse biased
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(c) diffusion in both forward and reverse biased
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(d) drift in both forward and reverse biased
[Understanding, average]
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16. Which of the junction diodes shown below

(a) (b) (c) (d)

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[Analysis, below average]

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Section B: 2 Marks Questions (VSA Type)

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17. What do you mean by temperature coefficient of resistivity? What is its expression? Write its sign for

las metals, alloys and semiconductors or insulators.
ag(0.5,0.5,1)

ag [Understanding, below average]
18. Write (without derivation) the expression of force acing per unit length between two long wires placed
parallel to each other in vacuum distance r away and carrying currents I1 and I2 in same direction. Hence
define 1 A of current. (1+1)
[Understanding, above average]
OR

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PSEB 12th Sample Paper 2027 Physics

A particle of charge q and mass m is moving with velocity v. It is subjected to a uniform magnetic field B
directed perpendicular to its velocity. Show that it describes a circular path. Write the expression for its
radius. (1+1)
[Understanding, above average]

19. (i) plot of magnetic flux (ϕ) versus current (I) is shown in the figure for two inductors A and B. Which
of the two has larger value of self-inductance?
(ii) A rod PQ of length 'l' is moved in uniform magnetic field 'B’ as shown. If the rod is moving with a
velocity 'v' making an angle 'θ' with magnetic field. What will be the emf induced in it? (1+1)

[Analysis, below average]
20. What is the origin of displacement current and write its formula? Also write expression of modified
Ampere circuital law. (1,1)
[Understanding, above average]
OR
Prove that energy of em radiations is distributed equally between the electric and magnetic field
components of em waves. (2)
[Understanding, above average]
21. What do you mean by impact parameter? Write its expression. (1,1)
[Knowledge, average]
22. (i) Why the barrier potential difference cannot be measured even by using sensitive voltmeter?
(ii) C, Si and Ge have same lattice structure, why carbon exists as an insulator, while Si and Ge are
intrinsic semiconductors? (1,1)
[Understanding, below average]
Section C: 3 Marks Questions (SA Type)
23. Find the expression for electric field due to a dipole on the equatorial line (broadside on position) and
also discuss the case when dipole is too short (r >> a). (2.5,0.5)
[Understanding, above average]
OR
Using Gauss law, derive an expression for electric field due to thin infinite long charged wire (charge
density λ) (3)
[Understanding, above average]
24. (i) Define the term ‘mobility’ of charge carriers. Write its S.I. unit. (0.5,0.5)
[Knowledge, average]
(ii) When 5 V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is
2.5 × 10-4 m/s if the electron density in the wire is 8 x 1028 m-3, calculate the resistivity of the material of
wire. (2)

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m .co s e m PSEB 12th Sample Paper 2027 Physics

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a [Application, average] ag
25. (i) For a para magnetic material, the dependence of the magnetic susceptibility χ on the absolute
temperature is given as (a) χ ∝ T (b) χ ∝ 1/T2 (c) χ ∝ 1/T (d) independent (1)
[Knowledge, average]
(ii) Point out the role of soft iron core inside the galvanometer. Also define radial magnetic field and give
its significance. (1,0.5,0.5)
[Analyze, below average]
26. (i) Show that L/R has the dimensions of time.
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[knowledge, average]
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(ii) A capacitor blocks DC and allows AC why?
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[Understanding, average] m l as
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(iii) An ordinary moving coil ammeter used for DC can’t be used to measure an AC even if its frequency is
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low.
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[Understanding, average] (1,1,1)
OR
(i) Interpret Faraday’s second law of electromagnetic induction. (1)
[knowledge, average]
(ii) The wire loops are shown moving inside or outside a magnetic field directed inwards. Using Lenz’s
law, find the direction of induced current in these loops. (0.5×4 = 2)
[Understanding, average]
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a 27. A point object O is kept in a medium of refractive index µ in front of a convex spherical surface of
1
radius of curvature R which separates the second medium of refractive index µ2 from the first one. Draw
the ray diagram showing the image formation and deduce the relationship b/w the object distance and the
image distance in terms of µ1, µ2 and R. (3)
[Knowledge, average]

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PSEB 12th Sample Paper 2027 Physics

OR
Prove laws of refraction on the basis of Huygens wave theory of light. (3)
[Knowledge, average]
28. (i) Differentiate between a ray and a wavefront. What is the phase difference between any two points
on a wavefront? (0.5,0.5)
[Knowledge, below average]
(ii) Show by drawing ray diagrams how a totally reflecting glass prism can be used to deviate a ray of light
through (a) 90o (b) 180o inside it? (1,1)
[Analysis, average]
29. (i) If the wavelength of an electromagnetic radiation is doubled, what will happen to (a) the energy of
the photons (b) the momentum of photons? (0.5,0.5)
[Knowledge, average]
(ii) The work function for Na is 2.75 eV and that for Mo is 4.175 eV. Which of these will not be able to
emit photo electrons when exposed to a wavelength of 330 nm? Why? If the source is brought closer, what
will be the effect on kinetic energy of the electrons emitted? (1.5,0.5)
[Application, above average]
30. (i) Doping of Si with Indium leads to which type of semiconductor? Give one more example of this
type. (0.5,0.5)
[Knowledge, average]
(ii) An n-type semiconductor has a large number of electrons but still it is electrically neutral. Explain. (1)
[Understanding, below average]
(iii) A potential barrier of 0.50 V exists in a p-n junction. If the depletion region is 5.0 × 10–7 m thick, what
is the electric field in this region? (1)
[Application, average]
Section D: Case Study Based Question (3 Marks)
31. When an atomic gas or vapour is excited usually by passing an electric current through it, the
gas/vapour emits radiations of certain specific wavelengths only. A spectrum of this kind is called Line
emission spectrum. It consists of a few bright lines on a dark background.
1 1 1
Balmer found an empirical relation to account for these wavelengths where = R( 2 − ), where n = 3,
𝜆 2 𝑛2
4, 5
Here, R is constant = 1.097 x 107 m-1. It is called Rydberg constant. n is an integer having values 3, 4, 5......
etc.
For n = 3 we get λ = 656.3 nm This is Hα line.
For n = 4 we get λ = 486.1 nm This is Hβ line.
For n = ∞ we get λ = 364.6 nm, which is the limit of Balmer series. Beyond this limit, the spectrum
becomes continuous, though faint. Thus Balmer series lies in visible region.
Later on, Lyman series was discovered in U.V. region of the spectrum.
Paschen series was discovered in infrared region.
Brackett series was discovered in infrared region.
Pfund series was discovered in infrared region.
Based on the above paragraph, answer questions (i) to (iii).

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m .co s e m PSEB 12th Sample Paper 2027 Physics

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as (i) When an atomic gas/vapour is excited by passing an electric current
ag through it, the gas/ vapour emits
radiations of (a) all wavelengths (b) all frequencies (c) certain specific wavelengths (d) none of these
[Knowledge, above average]
(ii) The maximum wavelength in Balmer series is produced when electron jumps from n2 to n1 level where
(a) n1 = 1, n2 = ∞ (b) n1 = 1, n2 = 2 (c) n1 = 2, n2 = 3 (b) n1 = 2, n2 = ∞
[understanding, below average]
(iii) Find the energy produced during Hβ emission in hydrogen atom spectrum.
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[Application, average]

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Section E: 5 Marks Questions (LA Type)
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32. (i) Define electric flux. Also state Gauss law in electrostatics. (1+1)
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[knowledge, above average]
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(ii) Make a graph of electric field due to a charged spherical shell (E) versus distance from centre (r) which
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clarifies the discontinuity of electric field at the surface of the shell. (1)
[Understanding, above average]
(iii) Two large thin metal plates are parallel and close to
each other. On their inner faces, the plates have surface
charge densities of opposite signs and magnitude 17.0 ×
10-22 Cm-2. What is E between the plates? (2)
[Application, above average]
OR
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(i) Write the formula (without derivation) of the capacity
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of a parallel plate capacitor. What is the effect on

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capacitance if the distance between plates is reduced to half and area of plates is doubled?
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(1+1)

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[knowledge, above average]
(ii) What will be the effect on the capacitance if the whole space between the plates is filled with some
medium of dielectric constant K? (1)
[Understanding, above average]
(iii) Calculate the area of paper required to construct a parallel plate capacitor of 0.004 μF, if the dielectric
constant of paper be 2.5 and its thickness 0.025 mm. (2)
[Application, above average]
33. (i) A proton and an electron travelling along parallel paths enter a region of uniform magnetic field
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acting perpendicular to their paths. Which of them will move in a circular path with higher frequency?
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Give answer with explanation. (1)

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[Understanding, above average]
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(ii) A square coil of side 10 cm has 20 turns and carries a current of 12 A. The coil is suspended vertically

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and normal to the plane of the coil makes an angle θ with the direction of a uniform horizontal magnetic
a field of 0.80 T. If the torque, experienced by the coil equals 0.96 N-m, find the value of θ. (2)
[Application, average]
(iii) Point out how a galvanometer can be converted into an ammeter and voltmeter. Also compare the
resistances of the three devices galvanometer, ammeter and voltmeter. (1+1)
[Analyze, below average]
OR

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PSEB 12th Sample Paper 2027 Physics

⃗ . ⃗⃗⃗⃗
(i) Give the significance of Gauss law in magnetism ∫𝑆 𝐵 𝑑𝑆 = 0. (1)
[Understanding, above average]
(ii) An electron in an atom revolves around the nucleus in an orbit of radius 0-5 Å. Calculate the equivalent
magnetic moment if the frequency of revolution of electron is 1010 MHz. (2)
[Application, average]
(iii) Categorize the materials given in the
figure among dia, para and ferro magnetic
substances. Also give at least one example
of each type. (1,1)
[Analyze, below average]
34. (i) Draw a labeled ray diagram to show
image formation by a compound microscope and write expression for its magnifying power when the final
image is obtained at least distance of distinct vision. (2)
[Understanding, above average]
(ii) The radii of curvature of the faces of a double convex lens are 10cm and 15 cm. If focal length of the
lens is 12 cm, find the refractive index of the material of the lens. (2)
[Application, above average]
(iii) A glass lens of refractive index 1.45 disappears when immersed in a liquid. What is the value of
refractive index of the liquid? (1)
[Analyze, below average]
OR
(i) Make a labeled diagram of diffraction of light at a single slit. Write the conditions (without derivation)
of path difference for the formation of diffraction maxima and minima. (2)
[Understanding, above average]
(ii) Two slits 0.125 mm apart are illuminated by light of wavelength 4500 Å. The screen is 1 m away, from
the plane of the slits. Find the separation between the 2nd bright fringe on both sides of the central
maximum. (2)
[Application, above average]
(iii) How diffraction of sound waves is easily observable in day to day life but diffraction of light is not so
common? (1)
[Analyze, below average]

Dr. Dinesh Kumar Hemraj Uppadhayaya Dev Raj
SCERT Nominee SCERT Nominee SCERT Nominee
Lecturer Physics Lecturer Physics Lecturer Physics
Govt. Victoria Girls Sr Sec School of Eminence GSSS Bhallan
School,Patiala-147001 Kapurthala-144601 Roopnagar
Mob: 9501399770 (Mob: 9463848890) Mob: 9877119509

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