(a) State the working principle of a potentiometer. With the help of the circuit diagram, explain how a potentiometer is used to compare the emf's of two primary cells. Obtain the required expression used for comparing the emfs.
(b) Write two possible causes for one sided deflection in a potentiometer experiment.

State the working principle of potentiometer. With the help of the circuit diagram, explain how a potentiometer is used to compare the emf's of two primay cells. Obtain the required expression used for comparing the emfs. Write two possible causes for one sided deflection in a potentiometer experiment.

State the principle of potentiometer. With the help of circuit diagram, describe a method to find the internal resistance of a primary cell.

Write the principle of working of a potentiometer. Describe briefly, with the help of a circuit diagram, how a potentiometer is used to determine the internal resistance of a given cell.

Draw a labelled circuit diagram of a potentiometer to compare emfs of two cells. Write the working formula (Derivation not required).

Explain, with the help of a circuit diagram, the working of a photo diaode. Write briefly how it is used to detect the optical signals.

State working principle of potentiometer. Explain how the balance point shifts when value of resistor R increases in the circuit of potentiometer, given below.

Draw a labelled circuit diagram of a potentiometer to measure internal resistance of a cell. Write the working formula. (Derivation not required).

(a) State the underlying principle of a potentiometer. Why is it necessary to (i) use a long wire, (ii) have uniform area of cross-section of the wire ? (b) Obtain an expression for equivalent capacitance when three capacitors C_(1), C_(2) "and" C_(3) are connected in series.

Draw a schematic arrangement for winding of primary and secondary coil in a transformer when the two coils are wound on top of each other. (ii) State the underlying principle of a transformer and obtain the expression for the ratio of secondary to primary voltage in terms of the (a) number of secondary and primary windings and (b) primary and secondary currents. (iii) Write the main assumption involved in deriving the above relations. (iv) Write any two reasons due to which energy losses may occur in actul transformers.

A potentiometer is used for the compaisem of e.m.f. of two cells E_(1) and E_(2) . For cell E_(1) the no deflection point os obtained at 20 cm and for E_(2) the no deflection point is obtained at 30 cm . The ratio of their e.m.f.'s will be