Two batteries of different e.m.f.'s and internal resistances are connected in series with each other and with an external load resistor. The current is 3.0 A. When the polarity of one battery is reversed, the current becomes 1.0 A. The ratio of the e.m.f.'s of the two batteries is:

1. 2.5

2. 2

3. 1.5

4. 1

In the figure, the e.m.f. of the cell is 2V and the internal resistance is negligible. The resistance of the voltmeter is 80 ohm. The reading of the voltmeter will be:

1. 2 volt

2. 1.33 volt

3. 1.60 volt

4. 0.80 volt

Calculate the current shown by ammeter A in the circuit diagram.

1. 0.1 A

2. 0.2 A

3. 0.3 A

4. 0.4 A

Ends A and B are connected to positive and negative terminals of a cell of emf 12 V respectively. The value of voltage shown by the voltmeter of negligible resistance is:

1. Zero

2. 3 V

3. 6 V

4. 12 V

In the circuit shown, R₁ is increased. What happens to the reading of the voltmeter (ideal)?

1. Increases

2. Decreases

3. First increases then decrease

4. Does not change

A combination of five resistors is connected to a cell of emf 10 V as shown in the figure. The potential difference ${\mathrm{V}}_{\mathrm{B}}-{\mathrm{V}}_{\mathrm{E}}$ will be

1. +5 V

2. +3 V

3. +1 V

4. Zero

In the meter bridge shown, the resistance X has a negative temperature coefficient of resistance. Neglecting the variation in other resistors, when current is passed for some time in the circuit, the balance point should shift towards:

1. A

2. B

3. First A then B

4. It will remain at C

Two cells of e.m.f. E₁ and E₂ are joined in series and the balancing length of the potentiometer wire is 625 cm. If the terminals of E₁ are reversed, the balancing length obtained is 125 cm. Given E₂>E₁, the ratio E₁:E₂ will be:

1. 2 : 3

2. 5 : 1

3. 3 : 2

4. 1 : 5

A 10 m long potentiometer wire is connected to a battery having a steady voltage. A Leclanche cell is balanced at 4 m length of the wire. If the length is kept the same, but its cross-section is doubled, the null point will be obtained at:

1. 8 m

2. 4 m

3. 2 m

4. None of these

Of the two bulbs in a household circuit, one glows brighter than the other. Which of the two bulbs has a large resistance?

1. The bright bulb

2. The dim bulb

3. Both have the same resistance

4. The brightness does not depend upon the resistance