Current Electricity · Question 19

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

A cell of emf 4 V and internal resistance 0.5 is connected to a 7.5 external resistance. The terminal potential difference of the cell is

1. 0.375 V
2. 3.75 V
3. 4.25 V
4. 4 V

The equivalent resistance of the infinite network given below is : [figure]

1. (1 + 5 )
2. 2
3. (1 + 2 )
4. (1 + 3 )

The sliding contact C is at one fourth of the length of the potentiometer wire (AB) from A as shown in the circuit diagram. If the resistance of the wire AB is R0, then the potential drop (V) across the resistor R is [figure]

1. 2V0 R2R0 + 3R
2. 4V0 R3R0 + 16R
3. 4V0 R3R0 + R
4. 2V0 R4R0 + R