Free question test - Physics 12

Current Electricity

1. Discuss the mechanism of metallic conduction. Derive a relation between current density and drift velocity.

2. How is a galvanometer converted into an ammeter and to voltmeter? Explain?

3. Distinguish between resistance and resistivity. Derive expression for the effective resistance of number of resistors, connected in series and parallel.
   Wave and Sound

4. What is resonance? How is the velocity of sound in air determined by resonance tube method?

5. What is the principle of super position as applied to wave motion? Discuss, the result of superposing two waves of equal amplitude and same frequency travelling in opposite direction.

6. What do you mean by phase oscillation and phase constant? Establish the equation of progressive wave.
   Magnetic Effect if Current

7. Define radial magnetic field. Derive an expression for the torque on a rectangular coil in a uniform magnetic field and mention the condition for maximum and minimum torque.

8. Derive an expression for the magnetic field intensity at a point due to a current carrying straight conductor of infinity length, using Biot-Savart law.

9. Obtain an expression for the torque acting on a rectangular coil in a uniform magnetic field and also define magnetic moment.

Modern Physics

1. Describe J.J. Thomson’s experiment for determining the specific charge of an electron.
2. Describe the phenomenon of electrical discharge through gases.
3. Describe with necessary theory of Millikan’s oil drop experiment to determine the value of the charge particle in electric and magnetic field.
4. Discuss the productivity of cathode ray and its characteristics.