CBSE Class 12 Physics Set 3 - (55/4/3) Question Paper 2025 is available for download here. CBSE conducted Class 12 Physics exam on February 21, 2025 from 10:30 AM to 1:30 PM. The Physics theory paper is of 70 marks, and the internal assessment is of 30 marks.
Also Check: CBSE Class 12 Question Paper 2025 (All Subjects)
The Physics question paper includes the following types of questions:
- MCQs: 1 mark each
- Very short-answer questions: 2 marks each
- Short-answer type questions: 3 marks each
- Case-study based questions: 4 marks each
- Long-answer type questions: 5 marks each
CBSE Class 12 Physics Set 3 - (55/4/3) Question Paper 2025 with Solution PDF
| CBSE Official PDF | CD PDF | CD PDF with Solutions |
|---|---|---|
| Download official PDF 2.57 MB | Download Collegedunia PDF 0.71 MB | Download solutions PDF 0.98 MB |
CBSE Class 12 Physics 2025 Set 3 (55/4/3) Questions with Solutions
Two point charges \(Q\) and \(-q\) are held '\(r\)' distance apart in free space. A uniform electric field \(E\) is applied in the region perpendicular to the line joining the two charges. Which one of the following angles will the direction of the net force acting on charge \(-q\) make with the line joining \(Q\) and \(-q\) ?
Three wires \(A\), \(B\) and \(C\) of the same material have lengths and area of cross-sections as \(\left(2l,\,\dfrac{A}{2}\right)\), \((l, A)\) and \(\left(\dfrac{l}{2},\,2A\right)\), respectively. If the resistances of these wires are \(R_A\), \(R_B\) and \(R_C\) respectively, then :
A particle of mass \(m\) and charge \(q\) moves along \(y\)-axis in a region in which a uniform magnetic field \(\vec{B}\) is pointing along \(x\)-axis. The Lorentz force acting on the charge will point along :
A bar magnet is initially at right angles to a uniform magnetic field. The magnet is rotated till the torque acting on it becomes one-half of its initial value. The angle through which the bar magnet is rotated is :
Which of the following substances has magnetic permeability less than that of free space ?
The magnetic flux linked with a closed coil (in Wb) varies with time \(t\) (in s) as \(\phi = 5t^2 + 4t - 2\). If the resistance of the circuit is \(14\,\Omega\), the magnitude of induced current in the coil at \(t = 1\,\text{s}\) will be :
In an electromagnetic wave travelling in free space, the amplitude of magnetic field is \(6.0 \times 10^{-4}\,\text{T}\). The amplitude of its electric field is :
A long straight wire is held vertically and carries a steady current in upward direction. The shape of magnetic field lines produced by the current-carrying wire are :
The magnification produced by a spherical mirror is \(-2.0\). The mirror used and the nature of the image formed will be :
Choose the correct statement :
A beam of red light and a beam of blue light have equal intensities. Which of the following statements is true ?
Which of the following is an electrical conductor at room temperature?
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
Assertion (A): In double slit experiment, if one slit is closed, diffraction pattern due to the other slit will appear on the screen.
Reason (R): For interference, at least two waves are required.
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
Assertion (A): For monochromatic incident radiation, the emitted photoelectrons from a given metal have speed ranging from zero to a certain maximum value.
Reason (R): Each metal has a definite work function.
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
Assertion (A): n-type semiconductor is not negatively charged.
Reason (R): Neutral pentavalent impurity atom doped in intrinsic semiconductor (neutral) donates its fifth unpaired electron to the crystal lattice and becomes a positive donor.
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
Assertion (A): A series LCR circuit behaves as a pure resistive circuit at resonance.
Reason (R): At resonance, \( X_L = X_C \) gives \( \omega = \frac{1}{\sqrt{LC}} \).
In an intrinsic semiconductor, carrier's concentration is \(5 \times 10^{8}\,\text{m}^{-3}\). On doping with impurity atoms, the hole concentration becomes \(8 \times 10^{12}\,\text{m}^{-3}\).
(a) Identify (i) the type of dopant and (ii) the extrinsic semiconductor so formed.
(b) Calculate the electron concentration in the extrinsic semiconductor.
In Young's double slit experiment, the screen is moved 30 cm towards the slits. As a consequence, the fringe width of the pattern changes by 0.09 mm. If the slits separation used is 2 mm, calculate the wavelength of light used in the experiment.
The two surfaces of a biconvex lens are of radius of curvature '\(R\)' each. Obtain the condition under which its focal length '\(f\)' be equal to '\(R\)'. If one of the two surfaces of this lens is made plane, what will be the new focal length of the lens ?
In Bohr's model of hydrogen atom, find the percentage change in the radius of its orbit when an electron makes a transition from \(n = 3\) state to \(n = 2\) state.
In the given figure, three identical bulbs \(P\), \(Q\) and \(S\) are connected to a battery.
(i) Compare the brightness of bulbs \(P\) and \(Q\) with that of bulb \(S\) when key \(K\) is closed.
(ii) Compare the brightness of the bulbs \(S\) and \(Q\) when the key \(K\) is opened.
Justify your answer in both cases.
Two cells of emf \(10\,\text{V}\) each, two resistors of \(20\,\Omega\) and \(10\,\Omega\) and a bulb \(B\) of \(10\,\Omega\) resistance are connected together as shown in the figure. Find the current that flows through the bulb.
(a) What are majority and minority charge carriers of p-type and n-type semiconductors ?
(b) Explain briefly the formation of diffusion current and drift current in a p-n junction diode.
(a) In which cases does a charged particle not experience a force in a magnetic field ?
(b) A square loop \(MNPK\) of side '\(l\)' carrying a current '\(I_2\)' is kept close to a long straight wire in the same plane and the wire carries a steady current \(I_1\), as shown in the figure. Obtain the magnitude of magnetic force exerted by the wire on the loop.
(a) Obtain an expression for the self-inductance of a long solenoid of length '\(l\)', cross-sectional area '\(A\)' and having '\(N\)' turns.
(b) The figure shows the plot of magnitude of induced emf (\(|\varepsilon|\)) versus the rate of change of current in two coils '1' and '2'. Which coil has greater value of self-inductance and why ?
Explain the following observations using Einstein's photoelectric equation :
(a) Photoelectric emission does not occur from a surface when the frequency of the light incident on it is less than a certain minimum value.
(b) It is the frequency, and not the intensity of the incident light which affects the maximum kinetic energy of the photoelectrons.
(c) The cut-off voltage (\(V_0\)) versus frequency (\(\nu\)) of the incident light curve is a straight line with a slope \(\dfrac{h}{e}\).
(a) Write the conditions under which two light waves originating from two coherent sources can interfere each other (i) constructively, and (ii) destructively, in terms of wavelength. Can these be applied for two lights originating from two sodium lamps ? Give reason.
(b) Monochromatic light of green colour is used in Young's double slit experiment and an interference pattern is observed on a screen. If the green light is replaced by red monochromatic light of the same intensity, how will the fringe width of interference pattern be affected ? Justify your answer.
(i) Derive an expression for the resistivity of a conductor in terms of number density of free electrons and relaxation time.
(ii) The figure shows the plot of current through a cross-section of wire over two different time intervals. Compare the charges (\(Q_1\) and \(Q_2\)) that pass through the cross-section during these time intervals.
(i) A battery of emf \(E\) and internal resistance \(r\) is connected to a variable external resistance \(R\).
(I) Obtain the expression for current \(I\) in the circuit and the value of maximum current the battery can supply.
(II) Obtain the terminal voltage \(V\) across the battery and its maximum possible value.
(ii) The above battery sends a current \(I_1\) when \(R = R_1\) and a current \(I_2\) when \(R = R_2\). Obtain the internal resistance of the battery in terms of \(I_1\), \(I_2\), \(R_1\) and \(R_2\).
(a) State any three characteristics of electromagnetic waves.
(b) Briefly explain how and where the displacement current exists during the charging of a capacitor.
Comprehension:
Case Study (Q30): A hydrogen atom consists of an electron revolving in a circular orbit of radius \(r\) with certain velocity \(v\) around a proton located at the nucleus of the atom. The electrostatic force of attraction between the revolving electron and the proton provides the requisite centripetal force to keep it in the orbit. According to Bohr's model, an electron can revolve only in certain stable orbits. The angular momentum
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of the electron in these orbits is some integral multiple of \(\dfrac{h}{2\pi}\), where \(h\) is the Planck's constant. Further, when an electron makes a transition from one orbit of higher energy to that of lower energy, a photon is emitted having energy equal to the difference between energies of the initial and final states. Assuming the mass and charge of an electron as \(m\) and \(e\) respectively, answer the following questions.(i) The expression for the speed of electron \(v\) in terms of radius of the orbit (\(r\)) and physical constant \(\left(K = \dfrac{1}{4\pi\varepsilon_0}\right)\) is :
The total energy of the atom in terms of \( r \) and physical constant \( K \) is:
(iii) A photon of wavelength \(500\,\text{nm}\) is emitted when an electron makes a transition from one state to the other state in an atom. The change in the total energy of the electron and change in its kinetic energy in eV as per Bohr's model, respectively will be :
(iv) In Bohr's model of hydrogen atom, the frequency of revolution of electron in its \(n^{\text{th}}\) orbit is proportional to :
An electron makes a transition from \(-3.4\ \text{eV}\) state to the ground state in hydrogen atom. Its radius of orbit changes by: (radius of orbit of electron in ground state = \(0.53\ \text{\AA}\))
Comprehension:
Case Study (Q29): A parallel plate capacitor consists of two conducting plates kept generally parallel to each other at a distance. When the capacitor is charged, the charge resides on the inner surfaces of the plates and an electric field is set up between them. Thus, electrostatic energy is stored in the capacitor. The figure shows three large square metallic plates, each of side '\(L\)' held parallel and
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equidistant from each other. The space between \(P_1\) and \(P_2\) and \(P_2\) and \(P_3\) is completely filled with mica sheets of dielectric constant '\(K\)'. The plate \(P_2\) is connected to point \(A\) and other plates \(P_1\) and \(P_3\) are connected to point \(B\). Point \(A\) is maintained at a positive potential with respect to point \(B\) and the potential difference between \(A\) and \(B\) is \(V\).(i) The capacitance of the system between \(A\) and \(B\) will be :
(ii) The charge on plate \(P_2\) is :
(iii) The electric field in the region between \(P_1\) and \(P_2\) is :
(iv) The separation between the plates of same area (\(L^2\)) of a parallel plate air capacitor having capacitance equal to that of this system, will be :
(iv) OR: If the source of potential difference applied between \(A\) and \(B\) is removed, and then \(A\) and \(B\) are connected by a conducting wire, the net charge on the system will be :
(i) An object is placed \(30\,\text{cm}\) from a thin convex lens of focal length \(10\,\text{cm}\). The lens forms a sharp image on a screen. If a thin concave lens is placed in contact with the convex lens, the sharp image on the screen is formed when the screen is moved by \(45\,\text{cm}\) from its initial position. Calculate the focal length of the concave lens.
(ii) Calculate the angle of minimum deviation of an equilateral prism. The refractive index of the prism is \(\sqrt{3}\). Calculate the angle of incidence for this case of minimum deviation also.
(i) A physics teacher wants to demonstrate interference with the help of double slit experiment using a laser beam of \(633\,\text{nm}\) wavelength. Since the hall is large enough, interference pattern is formed on the wall \(5.0\,\text{m}\) from the slits. For clear and comfortable view by all the students they want the fringe width \(5\,\text{mm}\).
(I) Find the slit separation for obtaining the desired interference pattern.
(II) How far will the first minimum be from the central maximum ?
(ii) A parallel beam of light of wavelength \(650\,\text{nm}\) passes through a slit of width \(0.6\,\text{mm}\). The diffraction pattern is obtained on a screen kept \(60\,\text{cm}\) away from the slit. Find the distance between first order minima on both sides of the central maximum.
(i) Two point charges \(+q\) and \(-q\) are held at \((a, 0)\) and \((-a, 0)\) in \(x\)-\(y\) plane. Obtain an expression for the net electric field due to the charges at a point \((0, y)\). Hence, find electric field at a far off point \((y \gg a)\).
(ii) Three point charges of \(-2\,\text{nC}\), \(-1\,\text{nC}\), and \(+5\,\text{nC}\) are kept at the vertices \(A\), \(B\) and \(C\) of an equilateral triangle of side \(0.2\,\text{m}\). Find the total amount of work done in shifting the charges from \(A\) to \(A_1\), \(B\) to \(B_1\) and \(C\) to \(C_1\). Here \(A_1\), \(B_1\) and \(C_1\) are the midpoints of sides \(AB\), \(BC\) and \(CA\), respectively.
(i) Show that Gauss's theorem is consistent with Coulomb's law. Using it, derive an expression for the electric field due to a uniformly charged thin spherical shell of radius \(r\) at a point at a distance \(y\) from the centre of the shell such that (I) \(y \gt r\), and (II) \(y \lt r\).
(ii) A point charge of \(+2\,\text{nC}\) is kept at the origin of a three-dimensional coordinate system. Find the type and magnitude of the charge which should be kept at \((0, 0, -6\,\text{m})\) so that the potential due to the system becomes zero at \((0, 0, 2\,\text{m})\).
(i) State Lenz's law and explain how this law is a consequence of conservation of energy principle.
(ii) A square shaped loop of side \(\dfrac{\ell}{2}\) is initially lying outside a region of uniform magnetic field \(\vec{B}\) as shown in the figure. The loop is moved towards right with a constant velocity \(\vec{v}\) till it goes out of the region of magnetic field.
(I) What will be the directions of induced current when the loop enters the field and when it leaves the field ?
(II) Draw the plots showing the variation of magnetic flux \(\phi\) linked with the loop with time \(t\) and variation of induced emf \(E\) with time \(t\). Mark the relevant values of \(E\), \(\phi\) and \(t\) on the graphs.
(i) Differentiate between peak and rms values of alternating current. How are they related ?
(ii) A current element \(X\) is connected across an ac source of emf \(V = V_0 \sin 2\pi \nu t\). It is found that the voltage leads the current in phase by \(\dfrac{\pi}{2}\) radian. If element \(X\) was replaced by element \(Y\), the voltage lags behind the current in phase by \(\dfrac{\pi}{2}\) radian.
(I) Identify elements \(X\) and \(Y\) by drawing phasor diagrams.
(II) Obtain the condition of resonance when both elements \(X\) and \(Y\) are connected in series to the source and obtain expression for resonant frequency. What is the impedance value in this case ?
CBSE Class 12 Physics Question Paper Pattern 2025
The CBSE Class 12 Physics 2025 question paper is of 70 marks and has 33 questions in five sections, A to E, all compulsory, with internal choice in some questions of Sections B to E. The time allowed is 3 hours, with 15 minutes of extra reading time. The table below gives the section-wise paper pattern from the official CBSE question paper.
| Section | Questions | Question Type | Marks per Question | Marks |
|---|---|---|---|---|
| A | Q1 - Q16 | Multiple choice questions | 1 | 16 |
| B | Q17 - Q21 | Very short answer questions | 2 | 10 |
| C | Q22 - Q28 | Short answer questions | 3 | 21 |
| D | Q29 - Q30 | Case study-based questions | 4 | 8 |
| E | Q31 - Q33 | Long answer questions | 5 | 15 |
| Total | 33 questions | 70 |
CBSE Class 12 Physics Unit-Wise Topics with Marks Distribution
| Unit No. | Unit Name | Chapters | Allotted Marks |
|---|---|---|---|
| Unit 1 | Electrostatics | Electric Charges and Fields | 16 |
| Electrostatic Potential and Capacitance | |||
| Unit 2 | Current Electricity | Current Electricity | |
| Unit 3 | Magnetic Effects of Current and Magnetism | Moving Charges and Magnetism | 17 |
| Magnetism and Matter | |||
| Unit 4 | Electromagnetic Induction and Alternating Current | Electromagnetic Induction | |
| Alternating Current | |||
| Unit 5 | Electromagnetic Waves | Electromagnetic Waves | 18 |
| Unit 6 | Optics | Ray Optics and Optical Instruments | |
| Wave Optics | |||
| Unit 7 | Dual Nature of Radiation and Matter | Dual Nature of Radiation and Matter | 12 |
| Unit 8 | Atoms and Nuclei | Atoms | |
| Nuclei | |||
| Unit 9 | Electronic Devices | Semiconductor Electronics: Materials, Devices, and Simple Circuits | 07 |
| Total | 70 | ||
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