Class 12 Physics Sample Paper (CBSE)
Time: 3 hours
Maximum Marks: 70
General Instructions:
- Read the questions carefully before attempting them.
- All questions are compulsory unless explicitly stated.
- For numerical problems, assume appropriate values for any missing data unless specified otherwise.
Section A (Short Answer Questions) (35 marks)
1. A parallel plate capacitor with plate area A and plate separation d is filled with a dielectric material of permittivity \(\epsilon\). (4 marks)
a) Derive an expression for the capacitance of the capacitor.
b) What is the effect of increasing the area of the plates on the capacitance? Justify your answer.
2. A ray of light travels from a medium with refractive index \(n_1\) to a medium with refractive index \(n_2\). (4 marks)
a) State Snell's law of refraction.
b) Derive an expression for the refractive index of the second medium relative to the first medium.
3. A charged particle of mass \(m\) and charge \(q\) is moving perpendicular to a magnetic field \(\overrightarrow{B}\). (4 marks)
a) State the Lorentz force acting on the particle.
b) Derive an expression for the radius of the circular path followed by the particle.
4. An inductor of inductance \(L\) is connected in series with a resistor \(R\) and a battery of emf \(\mathcal{E}\). (4 marks)
a) Write down the differential equation governing the current \(i(t)\) in the circuit.
b) Determine the time constant of the circuit.
5. Two coherent sources of light with wavelengths \(\lambda_1\) and \(\lambda_2\) interfere with each other. (4 marks)
a) Explain the concept of constructive interference.
b) Derive an expression for the fringe width in a double-slit experiment.
Section B (Long Answer Questions) (35 marks)
6. Derive the equation for the electric field at a point due to a point charge using Gauss's law. Also, explain the significance of Gauss's law in electrostatics. (6 marks)
7. Explain the concept of electromagnetic induction and Faraday's law. Derive an expression for the induced emf in a conducting rod moving in a magnetic field. (6 marks)
8. Describe the Bohr model of the atom and explain the significance of the quantum numbers \(n\), \(l\), and \(m_l\). (6 marks)
9. Discuss the phenomenon of superconductivity. Explain the differences between type I and type II superconductors. (6 marks)
10. Derive the de Broglie relation and explain the wave-particle duality of matter. (7 marks)
Note: This sample paper covers various topics from different chapters of class 12th Physics based on the CBSE curriculum. For a comprehensive understanding, it's important to refer to the prescribed textbook and additional study materials for a thorough preparation.