Current Electricity · Question 76

A student measures the terminal potential difference (V) of a cell (of emf and internal resistance r) as a function of the current (I) flowing through it. The slope, and intercept, of the graph between V and I, then respectively, equal

1. -r and
2. r and -
3. - and r
4. and -r

The mean free path of electrons in a metal is 4 10-8 m. The electric field which can give on an average 2 eV energy to an electron in the metal will be in units V/m

1. 5 10-11
2. 8 10-11
3. 5 107
4. 8 107

[figure] In the circuit shown, the current through the 4 resistor is 1 amp when the points P and M are connected to a d.c. voltage source. The potential difference between the points M and N is

1. 0.5 volt
2. 3.2 volt
3. 1.5 volt
4. 1.0 volt

A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively

1. both remain the same
2. 1.1 times, 1.1 times
3. 1.2 times, 1.1 times
4. 1.21 times, same

A cell can be balanced against 110 cm and 100 cm of potentiometer wire, respectively without and with being short circuited through a resistance of 10 . Its internal resistance is

1. 2.0 ohm
2. zero
3. 1.0 ohm
4. 0.5 ohm

An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature 20 ? The temperature of boiling water is 100

1. 12.6 min
2. 4.2 min
3. 6.3 min
4. 8.4 min

A current of 3 amp. flows through the 2 resistor shown in the circuit. The power dissipated in the 5 resistor is [figure]

1. 1 watt
2. 5 watt
3. 4 watt
4. 2 watt

Three resistances, P, Q, R each of 2 and an unknown resistance S form the four arms of a Wheatstone bridge circuit. When a resistance of 6 is connected in parallel to S the bridge gets balanced. What is the value of S?

1. 3
2. 6
3. 1
4. 2

The total power dissipated in watt in the circuit shown here is [figure]

1. 40
2. 54
3. 4
4. 16

In the circuit shown, if a conducting wire is connected between points A and B, the current in this wire will [figure]

1. flow from B to A
2. flow from A to B
3. flow in the direction which will be decided by the value of V
4. be zero