Current Electricity · Question 23

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

In a potentiometer circuit a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?

1. 62 cm
2. 60 cm
3. 21.6 cm
4. 64 cm

The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is 0.25 . What will be the effective resistance if they are connected in series?

1. 4
2. 0.25
3. 0.5
4. 1

Column - I gives certain physical terms associated with flow of current through a metallic conductor. Column-II gives some mathematical relations involving electrical quantities. Match column-I and column-II with appropriate relations.

1. (A)-(R); (B)-(Q); (C)-(S); (D)-(P)
2. (A)-(R); (B)-(S); (C)-(P); (D)-(Q)
3. (A)-(R); (B)-(S); (C)-(Q); (D)-(P)
4. (A)-(R); (B)-(P); (C)-(S); (D)-(Q)

Three resistors having resistances r1, r2 and r3 are connected as shown in the given circuit. The ratio i3i1 of currents in terms of resistances used in the circuit is : [figure]

1. r2r1+r3
2. r1r2+r3
3. r2r2+r3
4. r1r1+r2