1. Describe briefly three experimentally observed features in the phenomenon of photoelectric effect.
2. Discuss briefly how wave theory of light cannot explain these features.

How is a galvanometer converted into a voltmeter and an ammeter? Draw the relevant diagrams and find the resistance of the arrangement in each case. Take resistance of galvanometer as G.

1. When an AC source is connected to an ideal capacitor, show that the average power supplied by the source over a complete cycle is zero.
2. A bulb is connected in series with a variable capacitor and an A.C. source as shown. What happens to the brightness of the bulb when the key is the capacitor is gradually reduced?

State the underlying principle of a potentiometer. Write two factors by which current sensitivity of a potentiometer can be increased. Why is a potentiometer preferred over a voltmeter for measuring the emf of a cell?

State the principle of a cyclotron. Show that the time period of revolution of particles in a cyclotron is independent of their speeds. Why is this property necessary for the operation of a cyclotron?

1. Draw a schematic ray diagram of a compound microscope when image is formed at distance of distinct vision.
2. Write the expression for resolving power of a compound microscope. How can the resolving power of a microscope be increased?

Derive an expression for the axial magnetic field of a finite solenoid of length 2l and radius r carrying current I. Under what condition does the field become equivalent to that produced by a bar magnet?

In the given diagram, a coil B is connected to low voltage bulb L and placed parallel to another coil A as shown. Explain the following observations:

1. Bulb lights.
2. Bulb gets dimmer if the coil B moves upwards.