If the ammeter in the given circuit reads 2 A, the resistance R is :

(1) 1 ohm

(2) 2 ohm

(3) 3 ohm

(4) 4 ohm

Two resistances of 400 Ω and 800 Ω are connected in series with a 6-volt battery of negligible internal resistance. A voltmeter of resistance 10,000 Ω is used to measure the potential difference across 400 Ω. The error in the measurement of potential difference in volts approximately is :

(1) 0.01

(2) 0.02

(3) 0.03

(4) 0.05

A galvanometer, having a resistance of 50 Ω gives a full scale deflection for a current of 0.05 A. The length in meter of a resistance wire of area of cross-section 2.97× 10^–2 cm² that can be used to convert the galvanometer into an ammeter which can read a maximum of 5 A current is (Specific resistance of the wire = 5 × 10^–7 Ωm) 

(1) 9

(2) 6

(3) 3

(4) 1.5

An ammeter reads up to 1 ampere. Its internal resistance is 0.81 ohm. To increase the range to 10 A the value of the required shunt is :

(1) 0.09 Ω

(2) 0.03 Ω

(3) 0.3 Ω

(4) 0.9 Ω

The length of a wire of a potentiometer is 100 cm, and the emf of its standard cell is E volt. It is employed to measure the e.m.f of a battery whose internal resistance is 0.5 Ω. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is :

(1) $\frac{30E}{100}$

(2) $\frac{30E}{100.5}$

(3) $\frac{30E}{(100-0.5)}$

(4) $\frac{30(E-0.5i)}{100}$, where i is the current in the potentiometer

What is the reading of the voltmeter in the following figure?

(1) 3 V

(2) 2 V

(3) 5 V

(4) 4 V

The current flowing in a coil of resistance 90 Ω is to be reduced by 90%. What value of resistance should be connected in parallel with it 

(1) 9 Ω

(2) 90 Ω

(3) 1000 Ω

(4) 10 Ω

In a metre bridge experiment, the null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y 

(1) 50 cm

(2) 80 cm

(3) 40 cm

(4) 70 cm

In given figure, the potentiometer wire AB has a resistance of 5 Ω and length 10 m. The balancing length AM for the emf of 0.4 V is :

(1) 0.4 m

(2) 4 m

(3) 0.8 m

(4) 8 m

In a potentiometer experiment, the balancing with a cell is at length 240 cm. On shunting the cell with a resistance of 2 Ω, the balancing length becomes 120 cm. The internal resistance of the cell is :

1. 4 Ω

2. 2 Ω

3. 1 Ω

4. 0.5 Ω