Most important questions | Class 12 NEB Physics

Warning! The questions below are frequenty asked questions in NEB examination. Please follow the syllabus thoroughly. Every chapter and topic of your textbook is important. This questions are only for practice. Mechanics

1. Define moment of inertia. Derive an expression for the moment of inertia of thin uniform rod about an axis through its center and perpendicular to its length.
2. Derive a relation between the torque and angular acceleration in case of a rigid body.
3. State the conservation of angular momentum. Derive the relation between torque and angular momentum.
4. Write the physical significance of moment of inertia. Show that K.E. = \(\frac{1}{2} I \omega^2\) where the symbols have their usual meanings.
5. Define simple harmonic motion. Show that the bob of a simple pendulum may move with simple harmonic motion and find its time period.
6. Find an expression for the energy of particle in SHM and show that the particle obeys the law of conservation of energy.
7. On what factors do the rise and fall of the liquid on the capillary tube depend on? Show that \(T=\frac{h\rho g r}{2 cos\theta}\) where the symbols have their usual meanings.
8. Show that the surface tension is numerically equal to the suraface energy of a liquid.
9. State and prove Bernoulli's theorem.
Heat and Thermodynamics
10. Define thermodynamic process. Derive an equation of state for an adiabatic process.
11. Why is \(C_p\) greater than \(C_V\) in a gas. Derive the relation between them.
12. Describe the working of Carnot engine with the help of P-V diagram.
Wave and Optics
13. Define wave motion. Derive the progressive wave equations in a medium.
14. Starting with the definition of stationary waves, prove that the distance between any two consecutive nodes or antinodes in a stationary wave is \(\frac{\lambda}{2}\).
15. Write an expression for the Newton's formula for the velocity of sound in air. Explain the necessary correction made by Laplace.
16. Define end correction. Show that, in open organ pipe, both odd and even harmonics can be produced.
17. Define natural frequency. Describe an experiment to determine the velocity of sound in air by resonance air column tube method.
18. Describe sound wave as a pressure wave and deduce an expression for the pressure amplitude.
19. What is Doppler effect in sound? Obtain an expression for the apparent frequency of sound when both source and observer are moving towards each other.
20. State Huygen's law and use it to verify Snell's law.
21. Define coherent sources of light. Describe Young's double slit experiment and show that the bright fringes and dark fringes are equally spaced.
22. Define diffraction of light. Describe the diffraction of light at a single slit and find the condition for secondary maxima and minima.
23. Define polarization of light. Show that, \(\mu= tan\theta_p\), where the symbols have their usual meanings.


Electricity and Magnetism
24. How can you convert a galvanometer into ammeter (or voltmeter)? Explain.
25. State and apply Kirchoff's rule to measure the unknown resistance of a wire by using wheatstone bridge circuit.
26. State the principle of meter bridge. Describe how it is used to determine the resistance of a wire.
27. What is the principle of potentiometer? Explain with necessary theory how you would determine the internal resistance of the internal resistance of a cell using this principle.
28. What do you mean by thermo electric effect? Discuss the variation of thermo emf in a thermo couple with the change in temperature.
29. State and explain Biot - Savart's law. Use it to find the magnetic field due to a long straight current carrying conductor or solenoid or current carrying circular coil.
30. State Ampere's law. Deduce an expression for the force between two parallel current carrying wires.
31. State Faraday's law of electromagnetic induction. Derive an expression for the emf induced in a straight conductor moving at right angles to the direction of a uniform magnetic field.
32. State Faraday's law of electromagnetic induction. Deduce an expression for the emf induced in a coil rotating uniformly in a uniform magnetic field.
33. Explain the principle and working of a transformer.
34. Discuss the condition for resonant frequency of LCR alternating current circuit.
35. Derive an expression for the impedance of a LCR series a.c. circuit. Show graphically how impedance varies with the variation of applied frequency.


Modern Physics
36. Describe about construction and working principle of Millikan's oil drop experiment to determine the charge of an electron.
37. Define cross field. Describe construction and working principle of J.J. Thomson's experiment to determine specific charge of an electron.
38. Define threshold frequency and work function of a metal. Explain Einstein's photoelectric equation.
39. Describe the experiment to determine the Planck's constant.
40. State Bohr's postulates for atomic model. Derive the expression for radius of an electron bound to hydrogen atom . (OR, to find the total energy of an electron in n^th orbit.)
41. Explain Bragg's law of diffraction for X - rays.
42. State the laws of radioactivity. Derive the relation between half-life period and decay constant.

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