A milliammeter of range 0- 30 mA has internal resistance of 20 Ω. The resistance to be connected in series to convert it into a voltmeter of maximum reading 3V is

• 49 Ω

• 80 Ω

• 40 Ω

• 30 Ω

In the given circuit the equivalent resistance between the points A and B in ohms is

• 9

• 11.6

• 14.5

• 21.2

In the electric circuit shown each cell has an emf of 2V and internal resistance of 1Ω. The external resistance is 2Ω. The value of the current I is : (in amperes)

• 2

• 1.25

• 0.4

• 1.2

The radius of the coil of a TG which has 10 turns is 0.1 m. The current required to produce a deflection of 60° (B_h = 4 × 10^-5 T) is

• 3 A

• 1.1 A

• 2.1 A

• 1.5 A

A 5O mH coil carries a current of 2 A, the energy stored in joule is

• 1

• 0.05

• 0.1

• 0.5

An electric bulb is marked 100 W, 230 V. If the supply voltage drops to 115 V, what is the total energy produced by the bulb in 10 min ?

• 30 kJ

• 20 kJ

• 15 kJ

• 10 kJ

In the Wheatstone's bridge shown below, in order to balance the bridge we must have

• R₁ = 3 Ω, R₂ = 3 Ω

• R₁ = 6 Ω, R₂ = 1.5 Ω

• R₁ = 1.5 Ω, R₂ = any finite value

• R₁ = 3 Ω, R₂ = any finite value

118.

A resistor is constructed as hollow cylinder of dimensions r_a = 0.5 cm and r_b = 1.0 cm and ρ = 3 .5 x-10^-5 Ωm. The resistance of the configuration for the length of 5 cm cylinder is 

• 7.42 × 10^-3 Ω

• 10.56 × 10^-3 Ω

• 14.38 × 10^-3 Ω

• 16.48 × 10^-3 Ω

The resistances are connected as shown in the figure below. Find the equivalent resistance between the points A and B.

• 205 Ω

• 10 Ω

• 3.5 Ω

• 5 Ω

The figure below shows a 2.0 V potentiometer used for the determination of internal resistance of a 2.5 V cell. The balance point of the cell in the open circuit is 75 cm. When a resistor of 10 Ω is used in the external circuit of the cell, the balance point shifts to 65 cm length of potentiometer wire. Then the internal resistance of the cell is

• 2.5 Ω

• 2.0 Ω

• 1.54 Ω

• 1.0 Ω