Current Electricity

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

Which of the following acts as a circuit protection device?

1. inductor
2. conductor
3. switch
4. fuse

A set of n equal resistors, of value R each, are connected in series to a battery of emf E and internal resistance R. The current drawn is I. Now, the n resistors are connected in parallel to the same battery. Then the current drawn from battery becomes 10I. The value of n is

1. 10
2. 11
3. 20
4. 9

A battery consists of a variable number n of identical cells (having internal resistance r each) which are connected in series. The terminals of the battery are short-circuited and the current I is measured. Which of the graphs shows the correct relationship between I and n?

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