CBSE Class 12 Physics Question Paper 2026 PDF with Solutions - Available

1.

Explain the potential difference between the plates of a charged parallel plate capacitor decreases when its plates are brought closer.

2.

Obtain an expression for the work done to dissociate the system of three charges \(q\), \(-4q\) and \(2q\) placed at the vertices A, B and C respectively of an equilateral triangle of side \(a\).

3.

The electron drift speed is estimated to be only a few mm/s for currents in the range of a few amperes. How, then, is the current established almost the instant a circuit is closed ?

4.

The assertion that V = IR is a statement of Ohm’s law is not true. Why ?

5.

An equipotential surface through a point is normal to the electric field at that point.Explain

6.

An inductor of \(\frac{5}{\pi}\,H\), a capacitor of \(\frac{50}{\pi}\,\mu F\) and a resistor of \(400\,\Omega\) are connected in series across an ac voltage \[ v = 140 \sin(100\pi t)\,V. \] Calculate:
• (I) impedance of the circuit
• (II) rms value of current in the circuit} (Take \(\sqrt{2}=1.4\))

7.

Draw a labelled diagram of a step-up transformer. Obtain the ratio of secondary voltage to primary voltage in terms of number of turns in the two coils.

8.

The number of turns in the primary and the secondary coil of an ideal transformer are 100 and 5000 respectively. If 3.3 kW power is supplied to the transformer at 220 V, find:
• (I) current in the primary coil
• (II) output voltage

9.

An astronomical telescope consists of two converging lenses. One of them of large aperture and large focal length is called objective lens and the other one, of smaller focal length and smaller aperture is called the eyepiece. It is used to see distant objects which are not seen clearly with naked eyes. The image formed by the objective lens acts as an object for the eyepiece and the final image produced by the eyepiece is magnified.

10.

Two cells of emfs 12 V and 6 V are connected in parallel as shown in the figure. Their internal resistances are \(1\,\Omega\) and \(0.5\,\Omega\) respectively. Calculate the emf and internal resistance of the equivalent cell between points A and B.

11.

A low voltage supply from which one needs high currents must have very low internal resistance. Why ?

12.

Define the terms (I) resonant frequency, and (II) power factor of a series LCR circuit. For what value of the power factor will the power dissipated in the circuit be maximum?

13.

When a dielectric is placed in an external electric field, the electric field inside the dielectric is less than that outside it.Explain

14.

A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

15.

The momentum of a photon associated with a microwave of wavelength 4.00 cm is:

• \(1.66 \times 10^{-32}\) kg ms⁻¹
  
• \(1.83 \times 10^{-34}\) kg ms⁻¹
  
• \(2.05 \times 10^{-34}\) kg ms⁻¹
  
• \(1.66 \times 10^{-34}\) kg ms⁻¹