The galvanometer in the circuit shown here has a resistance of 20\(\Omega\)The terminals X and Y are connected to a cell of e.m.f. 1.5V and internal resistance 10\(\Omega\) Calculate the current flowing in the galvanometer:
(i) When the switch S is in position.
(ii) When the switch S is in position B.

A battery of e.m.f. 10V and internal resistance \(3\Omega \) is connected to a resistor. If the current in the circuit is 0.5A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?

Kirchhoff's junction rule is a reflection of 
(a) conservation of current density vector.
(b) conservation of charge
(c) the fact that the momentum with which a charged particle approaches a junction is unchanged as the charged particle leaves the junction.
(d) the fact that there is no accumulation of charges at a junction.

(a) Define electric current. What is its S.I. unit? Is it a scalar or a vector quantity? What is the direction of electric current?
(b) How many electrons flowing per second should flow to produce a current of 1A?

(a) State Ohm's law.
(b) Define resistance. Give its SI unit.

Establish the relation between current and drift velocity.

The unknown resistance of a conductor can be determined by Wheatstone bridge. The standard form of Wheatstone bridge is shown in the figure. It can be shown when the bridge is balanced.

\(\frac { P }{ Q } =\frac { R }{ S } \quad or\quad S=\frac { Q }{ P } R\)
Knowing P,Q and R, unknown resistance S can be calculated.
Read the above passage and answer the following questions.
(i) Name any two applications of Wheatstone bridge.
(ii) What is the practical utility of the post office box in day to day life?

Raghav lives in an area where birds in large groups play around producing pleasing humming sounds. One day he notices that the high power lines soon after a strong wind have come too close which may prove fatal for the birds that would sit on them and flutter their wings for some reason or other. He complained to the authorities and the lines were set at the proper distance once again.
(1) What are the values possessed by Raghav and the authorities?
(2) What is the danger that could happen to the innocent birds in Raghav's view?

(i) State the principle of working of a potentiometer.
(ii) In the following potentiometer circuit AB is a uniform wire of length 1 m and resistance 10 \(\Omega \) .Calculate the potential gradient along the wire and balance length AO (= l).

In the arrangement of resistors shown here, what fraction of I will pass through 5\(\Omega\) resistor?