CBSE Class 12 Physics Set 1 - (55/4/1) 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 1 - (55/4/1) Question Paper 2025 with Solution PDF
| CBSE Official PDF | CD PDF | CD PDF with Solutions |
|---|---|---|
| Download official PDF 2.46 MB | Download Collegedunia PDF 0.86 MB | Download solutions PDF 1.24 MB |
CBSE Class 12 Physics 2025 Set 1 (55/4/1) Questions with Solutions
A body acquires charge \(8.0 \times 10^{-12}\,\text{C}\). The mass of the body :
A current flows through a cylindrical conductor of radius \(R\). The current density at a point in the conductor is \(j = \alpha r\) (along its axis), here \(\alpha\) is a constant and \(r\) is distance from the axis of the conductor. The current flowing through the portion of the conductor from \(r = 0\) to \(r = \dfrac{R}{2}\) is proportional to :
A particle having charge \(+q\) enters a uniform magnetic field \(\vec{B}\) as shown in the figure. The particle will describe :
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 one out of the following materials is not paramagnetic ?
An ammeter connected in series in an AC circuit reads \( 10 \, \text{A} \). The maximum value of current at any instant in the circuit is:
The amplitude of electric field in an electromagnetic wave in free space is \(1000\,\text{V m}^{-1}\). The amplitude of the magnetic field in this electromagnetic wave is :
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 ?
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 :
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 \( \omega = \frac{1}{\sqrt{LC}} \).
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.
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.
Find the angle of diffraction (in degrees) for first secondary maximum of the pattern due to diffraction at a single slit. The width of the slit and wavelength of light used are \(0.55\,\text{mm}\) and \(550\,\text{nm}\), respectively.
An equiconvex lens is made of glass of refractive index \(1.55\). If the focal length of the lens is \(15.0\,\text{cm}\), calculate the radius of curvature of its surfaces.
Calculate the mass of an \(\alpha\)-particle in atomic mass unit (u). Given,
Mass of a normal helium atom \(= 4.002603\,\text{u}\)
Mass of carbon atom \(= 1.9926 \times 10^{-26}\,\text{kg}\)
In an intrinsic semiconductor, carrier's concentration is \(5 \times 10^{16}\,\text{m}^{-3}\). 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.
(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) Write vector form of Biot-Savart law.
(b) Two insulated long straight wires, each carrying \(2.0\,\text{A}\) current are kept along \(xx'\) and \(yy'\) axis as shown in the figure. Find the magnitude and direction of resultant magnetic field at point \(P(4\,\text{m},\,5\,\text{m})\).
Two coils '1' and '2' are placed close to each other as shown in the figure. Find the direction of induced current in coil '1' in each of the following situations, justifying your answers :
(a) Coil '2' is moving towards coil '1'.
(b) Coil '2' is moving away from coil '1'.
(c) The resistance connected with coil '2' is increased keeping both the coils stationary.
(a) State any three characteristics of electromagnetic waves.
(b) Briefly explain how and where the displacement current exists during the charging of a capacitor.
A double slit set-up was initially placed in a tank filled with water and the interference pattern was obtained using a laser light. When water is replaced by a transparent liquid of refractive index \(n \gt n_{\text{water}}\), what will be the effect on the following ?
(a) Speed, frequency and wavelength of the light of laser beam.
(b) The fringe width, shape of interference fringes and shift in the position of central maximum.
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) 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.
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 :
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 = \(0.53\ \text{\AA}\))
(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 ?
(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.
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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