The potentiometer wire AB is 600 cm long. At what distance from A should the jockey J touch the wire to get zero deflection in the galvanometer?

        

1. 320 cm

2. 120 cm

3. 20 cm

4. 450 cm

A torch bulb rated 4.5 W, 1.5 V is connected as shown in the figure below. The emf of the cell needed to make the bulb glow at full intensity is:

1. 4.5 V

2. 1.5 V

3. 2.67 V

4. 13.5 V

The metre bridge shown is in a balanced position with \(\frac{P}{Q} = \frac{l_1}{l_2}\). If we now interchange the position of the galvanometer and the cell, will the bridge work? If yes, what will be the balanced condition?

    
1. Yes, \(\frac{P}{Q}=\frac{l_1-l_2}{l_1+l_2}\)
2. No, no null point
3. Yes, \(\frac{P}{Q}= \frac{l_2}{l_1}\)
4. Yes, \(\frac{P}{Q}= \frac{l_1}{l_2}\)

A battery of internal resistance r, when connected across \(2~\Omega\) resistor supplies a current of 4 A. When the battery is connected across a \(5~\Omega\) resistor, it supplies a current of 2 A. The value of r is: 

In the circuit shown in the figure below, the current supplied by the battery is:

1.  2 A

2.  1 A

3.  0.5 A

4.  0.4 A

The equivalent resistance between points A and B in the circuit shown in the figure is:

1.  6R

2.  4R

3.  2R

4.  R

In the circuit shown in the figure below, if the potential difference between B and D is zero, then value of the unknown resistance X is:

The figure below shows a network of currents. The current \(i\) will be:

1. \(3~\mathrm{A}\)
2. \(13~\mathrm{A}\)
3. \(23~\mathrm{A}\)
4. \(-3~\mathrm{A}\)

Eels are able to generate current with biological cells called electroplaques. The electroplaques in an eel are arranged in 100 rows, each row stretching horizontally along the body of the fish containing 5000 electroplaques. The arrangement is suggestively shown below. Each electroplaques has an emf of 0.15 V and internal resistance of 0.25 Ω.

The water surrounding the eel completes a circuit between the head and its tail. If the water surrounding it has a resistance of 500 Ω, the current an eel can produce in water is about:

1. 1.5 A

2. 3.0 A

3. 15 A

4. 30 A

A potentiometer wire has a length 4 m and resistance 8 Ω. The resistance that must be connected in series with the wire and an energy source of emf 2 V, so as to get a potential gradient 1 mV per cm of the wire is:
1. 32 Ω
2. 40 Ω
3. 44 Ω
4. 48 Ω