Current Electricity

The magnitude and direction of the current in the following circuit is :- [figure]

1. 0.5 A from A to B through E
2. 59 A from A to B through E
3. 1.5 A from B to A through E
4. 0.2 A from B to A through E

If the galvanometer G does not show any deflection in the circuit shown, the value of R is given by: [figure]

1. 50
2. 100
3. 400
4. 200

Resistance of a carbon resistor determined from colour codes is (22000 5\%) . The colour of third band must be :

1. Green
2. Orange
3. Yellow
4. Red

The resistance of platinum wire at 0 is 2 and 6.8 at 80 . The temperature coefficient of resistance of the wire is :

1. 3 10-3 -1
2. 3 10-2 -1
3. 3 10-10 -1
4. 3 10-4 -1

10 resistors, each of resistance R are connected in series to a battery of emf E and negligible internal resistance. Then those are connected in parallel to the same battery, the current is increased n times. The value of n is :

1. 100
2. 1
3. 1000
4. 10

As the temperature increases, the electrical resistance

1. Increases for both conductors and semiconductors
2. Decreases for both conductors and semiconductors
3. Increases for conductors but decreases for semiconductors
4. Decreases for conductors but increases for semiconductors

Two resistors of resistance, 100 and 200 are connected in parallel in an electrical circuit. The ratio of the thermal energy developed in 100 to that in 200 in a given time is

1. 1 : 2
2. 2 : 1
3. 1 : 4
4. 4 : 1

A copper wire of length 10 m and radius ( 10-2 ) m has electrical resistance of 10 . The current density in the wire for an electric field strength of 10 (V/m) is

1. 104 A/m2
2. 106 A/m2
3. 10-5 A/m2
4. 105 A/m2

A wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistance P and Q [figure]

1. Should be approximately equal to 2X
2. Should be approximately equal and are small
3. Should be very large and unequal
4. Do not play any significant role

The reciprocal of resistance is :

1. conductance
2. reactance
3. mobility
4. conductivity