Current Electricity · Question 30

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

A resistance wire connected in the left gap of a metre bridge balances a 10 resistance in the right gap at a point which divides the bridge wire in the ratio 3:2. If the length of the resistance wire is 1.5 m, then the length of 1 of the resistance wire is :

1. 1.0 10-1 m
2. 1.5 10-1 m
3. 1.5 10-2 m
4. 1.0 10-2 m

The color code of a resistance is given below : [figure] The values of resistance and tolerance, respectively, are

1. 47 k , 10%
2. 4.7 k , 5%
3. 470 , 5%
4. 470 k , 5%

A charged particle having drift velocity 7.5 10-4 m s-1 in an electric field of 3 10-10 V m-1 has a mobility in m2 V-1 s-1 of :

1. 2.5 106
2. 2.5 10-6
3. 2.25 10-15
4. 2.25 1015

Which of the following graph represents the variation of resistivity ( ) with temperature (T) for copper?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

The solids which have the negative temperature coefficient of resistance are :

1. insulators only
2. semiconductors only
3. insulators and semiconductors
4. metals

Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero internal resistance. The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section A and one from section B are glowing, will be : [figure]

1. 4 : 9
2. 9 : 4
3. 1 : 2
4. 2 : 1

In the circuits shown below, the readings of voltmeters and the ammeters will be : [figure]

1. V1 = V2 and i1 = i2
2. V1 > V2 and i1 > i2
3. V1 > V2 and i1 = i2
4. V1 = V2 and i1 > i2