A current of 2 A flows in a system of conductors as shown. The potential difference $(V_A-V_B)$ will be 

1. +2 V

2. +1 V

3. –1 V

4. –2 V

Four resistances are connected in a circuit in the given figure. The electric current flowing through 4 ohm and 6 ohm resistance is respectively 

1. 2 amp and 4 amp

2. 1 amp and 2 amp

3. 1 amp and 1 amp

4. 2 amp and 2 amp

In the given figure, when key K is opened, the reading of the ammeter A will be

1. 50 A

2. 2 A

3. 0.5 A

4. $\frac{10}{9}A$

Three equal resistances each of value R are joined as shown in the figure. The equivalent resistance between M and N is 

1. R

2. 2R

3. $\frac{R}{2}$

4. $\frac{R}{3}$

The figure below shows currents in a part of electric circuit. The current i is

1. 1.7 amp

2. 3.7 amp

3. 1.3 amp

4. 1 amp

For measurement of potential difference, the potentiometer is preferred in comparison to the voltmeter because:

1. the potentiometer is more sensitive than the voltmeter.

2. the resistance of the potentiometer is less than
    the voltmeter.

3. the potentiometer is cheaper than the voltmeter.

4. the potentiometer does not take current from the circuit.

In order to pass 10% of the main current through a moving coil galvanometer of 99 ohms, the resistance of the required shunt is :

1. 9.9 Ω

2. 10 Ω

3. 11 Ω

4. 9 Ω

A galvanometer can be used as a voltmeter by connecting a :

1. High resistance in series

2. Low resistance in series

3. High resistance in parallel

4. Low resistance in parallel

A potentiometer is used for the comparison of e.m.f. of two cells E₁ and E₂. For cell E₁ the no deflection point is obtained at 20cm and for E₂ the no deflection point is obtained at 30cm. The ratio of their e.m.f.'s will be 

1. 2/3

2. 1/2

3. 1

4. 2

Two cells when connected in series are balanced on 8m on a potentiometer. If the cells are connected with polarities of one of the cells  reversed, they balance on 2m. The ratio of e.m.f.'s of the two cells is

1. 3 : 5

2. 5 : 3

3. 3 : 4

4. 4 : 3