CBSE Class 12 Physics Term 1 Sample Paper 2025: Download FREE PDF With Solutions!

CBSE Class 12 Physics Term 1 Sample Paper 2025: Want to prepare for the Physics exam? Don’t worry, as we've got you covered. Check this article to get the CBSE Class 12th Physics Sample Paper 2025-26. 

CBSE Class 12 Physics Term 1 Sample Paper 2025: Download FREE PDF With Solutions

[SECTION – A] (16x1=16 marks)

Q1. A uniform electric field pointing in the positive X-direction exists in a region. Let A be the origin, B be the point on the X-axis at x = +1 cm, and C be the point on the Y-axis at y = +1 cm. Then the potential at points A, B and C satisfies.

(A) VA < VB (B) VA > VB. (C) VA < VC (D) VA > VC

Q2. A conducting wire connects two charged conducting spheres of radii r1 and r2 such that they attain equilibrium with respect to each other. The distance of separation between the two spheres is very large compared to either of their radii. The ratio of the magnitudes of the electric fields at the surfaces of the spheres of radii r1 and r2 is

(A)𝑟1/𝑟2

(B) 𝑟2/𝑟1(C)𝑟2²/𝑟1²

(D)𝑟1²/𝑟2²

Q3. A long straight wire of circular cross section of radius ҅a᾿ carries a steady current I. The current is uniformly distributed across its cross-section. The ratio of the magnitudes of the magnetic field at a point a/2 above the surface of the wire to that of a point a/2 below its surface is: 

(A) 4:1 (B) 1:1 (C) 4: 3 (D) 3: 4

Q4. The diffraction effect can be observed in

(A) sound waves only (B) light waves only

(C) ultrasonic waves only (D) sound waves as well as light waves

Q5. A capacitor consists of two parallel plates, with an area of cross-section of 0.001 m2, separated by a distance of 0.0001 m. If the voltage across the plates varies at the rate of 108 V/s, then the value of displacement current through the capacitor is:

(A) 8.85 × 10−3𝐴 (B) 8.85 × 10−4𝐴 (C) 7.85 × 10−3𝐴 (D) 9.85 × 10−3𝐴

Q6. In a series LCR circuit, the voltage across the resistance, capacitance and inductance is 10 V each. If the capacitance is short-circuited, the voltage across the inductance will be

(A) 10 V (B) 10√2 V (C) 10/√2 V (D) 20 V

Q7. Correct match of column I with column II 

(A) 1-P, 2-R, 3-S, 4-Q (B) 1-S, 2-P, 3-O, 4-R (C) 1-Q, 2-P, 3-S, 4-R (D) 1-S. 2-R, 3-P, 4-Q 

Q8. The distance of closest approach of an alpha particle is d when it moves with a speed V towards a nucleus. Another alpha particle is projected with higher energy such that the new distance of the closest approach is d/2. What is the speed of projection of the alpha particle in this case?

(A) V /2 (B) √2 V (C) 2 V (D) 4 V

Q9. A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The distance of the virtual image from the surface of the sphere is

(A) 2 cm (B) 4 cm (C) 6 cm (D) 12 cm

Q10. Colours observed on a CD (Compact Disk) are due to

(A) Reflection (B) Diffraction (C) Dispersion (D) Absorption

Q11. The number of electrons made available for conduction by dopant atoms depends strongly upon

(A)doping level (B) increases with ambient temperature

(C) energy gap (D) options (A) and (B) both

Q12. If copper wire is stretched to make its radius decrease by 0.1%, then the percentage change in its resistance is approximately

(A)–0.4% (B) +0.8% (C) +0.4% (D) +0.2%

For Questions 13 to 16, two statements are given –one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the options given below.

A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

B. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

C. If the Assertion is true but the Reason is false.

D. If both Assertion and Reason are false.

Q13. Assertion (A): Increasing the current sensitivity of a galvanometer by increasing the number of turns may not necessarily increase its voltage sensitivity.

Reason(R): The resistance of the coil of the galvanometer increases with the increase in the number of turns.

Q14. Assertion (A): In a hydrogen atom, there is only one electron but its emission spectrum shows many lines.

Reason (R): In a given sample of hydrogen, there are many atoms, each containing one electron; hence, many electrons in different atoms may be in different orbits, so many transitions from higher to lower orbits are possible.

Q15. Assertion (A): Nuclei having a mass number of about 60 are the least stable.

Reason (R): When two or more light nuclei are combined into a heavier nucleus, the binding energy per nucleon will decrease.

Q16. Assertion (A): de Broglie's wavelength of a freely falling body keeps decreasing with time.

Reason (R): The momentum of the freely falling body increases with time.

[SECTION: B]

17. The wavelength of the second line of the Balmer series in the Hydrogen atom is 4861A0. Calculate the wavelength of the first line.

18. A point object is placed at O in front of a glass sphere, as shown in the given figure. Show the formation of an image by the sphere.

19. When an alternating voltage of 220V is applied across an Inductor, a current of 0.25A flows, which lags behind the applied voltage in phase by π/2 radians. If the same voltage is applied across the resistor, the same current flows, but now it is in phase with the applied voltage. Calculate the current flowing in the circuit when the same voltage is applied across the series combination of the Inductor and the Resistor

20. (a) Define the current sensitivity of a galvanometer. Write its expression.

(b) A galvanometer has resistance G and shows full-scale deflection for current Ig. 

(i) How can it be converted into an ammeter to measure current up to I0 (I0 > Ig)?

OR

A long wire is bent into a circular coil of one turn and then into a circular coil of smaller radius having ‘n’ turns if the same current passes in both the coils. Find the ratio of the magnetic fields produced at the centre of the two coils. 

21. A long, rectangular, conducting loop of width l, mass m, and resistance R, placed partly in a perpendicular magnetic field B. With what velocity should it be pushed downwards so that it may continue to fall without any acceleration?

[SECTION – C ] (07x3=21 marks)

Q22. (I) Identify the circuit elements X and Y as shown in the given block diagram, and draw the output waveforms of X and Y.

(II) If the centre tapping is shifted towards Diode D1, as shown in the diagram, draw the output waveform of the given circuit.

Q23. Find the expression for the capacitance of a parallel plate capacitor of plate area A and plate separation

d when (I) a dielectric slab of thickness t and (II) a metallic slab of thickness t, where (t < d) are introduced one by one between the plates of the capacitor. In which case would the capacitance be more, and why?

Q24. (I) Draw a ray diagram for the formation of the image by a Cassegrain telescope.

(II)Why are these types of telescopes preferred over refracting-type telescopes? (Write 2 points)

Q25. (I) Draw the energy band diagram for a P-type semiconductor at (i) T=0K and (ii) room temperature.

(II)In the given diagram, considering an ideal diode, in what condition will the bulb glow

(a) when the switch is open,

(b) when the switch is closed

 Justify your answer.

Q26. A boy is holding a smooth, hollow and non-conducting pipe vertically with a charged spherical ball of mass 10 g carrying a charge of +10 mC inside it, which is free to move along the axis of the pipe.

The boy is moving the pipe from East to West in the presence of a magnetic field of 2T. With what minimum velocity should the boy move the pipe such that the ball does not move along the axis? Also, determine the direction of the magnetic field.

Q27. A light ray entering a right-angled prism undergoes refraction at the face AC as shown in Fig. 1.

(I) What is the refractive index of the material of the prism in Fig. 1?

(II) (a) If the side AC of the above prism is now surrounded by a liquid of refractive index 2/√3 as shown in Fig. 2, determine if the light ray continues to graze along the interface AC or undergoes total internal reflection or refraction into the liquid.

(b) Draw the ray diagram to represent the path followed by the incident ray with the corresponding angle values. (Given, 𝑠𝑖𝑛⁻¹(√2/√3) = 54.6°)

Q28. (I) State Gauss᾿s theorem in electrostatics. Using this theorem, derive an expression for the electric field due to an infinitely long straight wire of linear charge density.

OR

(II) (a) Define electric flux and write its SI unit.

(b) Use Gauss᾿s law to obtain the expression for the electric field due to a uniformly charged infinite plane sheet of charge.

SECTION-D

29. A dielectric with polar molecules also develops a net dipole moment in an external field, but for a different reason. In the absence of any external field, the different permanent dipoles are oriented randomly due to thermal agitation; so, the total dipole moment is zero. When an external field is applied, the individual dipole moments tend to align with the field. When summed overall, the molecules, there is then a net dipole moment in the direction of the external field, i.e., the dielectric is polarised. The extent of polarisation depends on the relative strength of two factors: the dipole potential energy in the external field tending to align the dipoles mutually opposite with the field, and thermal energy tending to disrupt the alignment. There may be, in addition, the ‘induced dipole moment’ effect as for non-polar molecules, but generally the alignment effect is more important for polar molecules. Thus, in either case, whether polar or non-polar, a dielectric develops a net dipole moment in the presence of an external field. The dipole moment per unit volume is called polarisation.

(i) The best definition of polarisation is

(a) Orientation of dipoles in a random direction 

(b) Electric dipole moment per unit volume

(c) Orientation of dipole moments 

(d) Change in polarity of every dipole

(ii) Calculate the polarisation vector of the material which has 100 dipoles per unit volume in a volume of 2 units.

(a) 200 (b) 50 (c) 0.02 (d) 100

(iii) The total polarisation of a material is the

(a) Product of all types of polarisation 

(b) Sum of all types of polarisation 

(c)Orientation directions of the dipoles 

(d)Total dipole moments in the

(iv) Dipoles are created when a dielectric is placed in

(a) Magnetic Field (b) Electric field (c) Vacuum (d) Inert Environment

OR

Identify which type of polarisation depends on temperature. 

(a)Electronic (b) Ionic (c) orientational (d) Interfacial

30. The telescope is used to provide angular magnification of distant objects. It also has an objective  4M and an eyepiece. But here, the objective has a large focal length and a much larger aperture than the eyepiece. Light from a distant object enters the objective, and a real image is formed in the tube at its second focal point. The eyepiece magnifies this image, producing a final inverted image. The magnifying power m is the ratio of the angle β subtended at the eye by the final image to the angle α which the object subtends at the lens or the eye.

(i)An astronomical telescope uses two lenses of powers 10 D and 1 D. Its magnifying power in normal adjustment is

(a) 20, (b)10, (c)0.05, (d)0.1

(ii)An astronomical telescope uses an objective lens of focal length of objective lens and an eyepiece are 150 m and 6 cm. In case the final image is formed at least the distance of distinct vision, the magnifying power is

(a)20 (b)30 (c)60 (d)15

(iii)You are given the following three lenses. Two lenses, which you will use as an eyepiece and as an objective to construct an astronomical telescope.

a)L1,L3

(b) L2,L3

(c)L3,L2

(d)L3,L

[SECTION E] (03X5=15)

Q31. (I) a) Write two limitations of Ohm’s law. Plot their I-V characteristics.

b) A heating element connected across a battery of 100 V having an internal resistance of 1 Ω draws an initial current of 10 A at room temperature 20.0 °C, which settles after a few seconds to a steady value. What is the power consumed by the battery itself after the steady temperature of 320.0 °C is attained? The temperature coefficient of resistance averaged over the temperature range involved is 3.70 × 10–4°C–1.

OR

(II) a) Using Kirchhoff'᾿s laws, obtain the equation of the balanced state in the Wheatstone bridge.

b) A wire of uniform cross-section and resistance of 12 ohms is bent in the shape ofa  circle as shown in the figure. A resistance of 10 ohms is connected to diametrically opposite ends C and D. A battery of emf 8V is connected between A and B. Determine the current flowing through arm AD.

Q32. (I) Explain briefly, with the help of a labelled diagram, the basic principle of the working of an a.c.

generator. In an a.c. A generator, coil of N turns and area A, is rotated at an angular velocity ω in a uniform magnetic field B. Derive an expression for the instantaneous value of the emf induced in the coil. What is the source of energy generation in this device?

OR

(II) a) With the help of a diagram, explain the principle of a device which changes a low AC voltage into a high voltage. Deduce the expression for the ratio of secondary voltage to the primary voltage in terms of the ratio of the number of turns of primary and secondary windings. For an ideal transformer, obtain the ratio of primary and secondary currents in terms of the ratio of the voltages in the secondary and primary coils.

b) Write any two sources of the energy losses which occur in actual transformers.

c) A step-up transformer converts a low input voltage into a high output voltage. Does it violate the law of conservation of energy? Explain.

Q33. (I) a) A giant refracting telescope at an observatory has an objective lens of focal length 15 m. If an

An eyepiece of focal length 1.0 cm is used; what is the angular magnification of the telescope in normal adjustment?

b) If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is 3.48 × 106 m, and the radius of the lunar orbit is 3.8 × 108 m.

OR

(II) A compound microscope consists of an objective lens of focal length 2.0 cm and an eyepiece of

focal length 6.25 cm, separated by a distance of 15 cm. How far from the objective should an object be placed to obtain the final image at

a) the least distance of distinct vision (25 cm) and

b) infinity? What is the magnifying power of the microscope in each case?

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