Current Electricity

Resistors P and Q are connected in the gaps of the meter bridge. The balancing point is obtained $\frac{1}{3}$ m from the zero end. If a 6 Ω resistance is connected in series with P the balance point shifts to $\frac{2}{3}$ m from the same end. P and Q are

• 4, 2

• 2, 4

• both (a) and (b)

• neither (a) nor (b)

The currents i₁ and i₂ through the resistors R₁ = 10 Ω and R₂ = 30 Ω in the circuit diagram with E₁ = 3 V , E₂ = 3 V and E₃ = 2 V are respectively

• 0.2 A, 0.1 A

• 0.4 A, 0.2 A

• 0.1 A, 0.2 A

• 0.2 A, 0.4 A

A milliammeter of range O - 30 mA has internal resistance of 20Ω.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

A thin wire of resistance 4Ω is bent to form a circle. The resistance across any diameter is

• 4 Ω

• 2 Ω

• 1 Ω

• 8 Ω

A battery of e.m.f. E and internal resistance r is connected to an external resistance R the condition for maximum power transfer is

• r < R

• r > R

• r = 1/R

• r = R

Two wires each of same material and same length have 2 : 1 ratio of their radii. If the first wire has a resistance of 2 Ω then what will be the equivalent resistance of the two wires when they are connected in series ?

What should be the resistance of an ideal ammeter and an ideal voltmeter ?

A 60 W- 220 V bulb is connected in series with another bulb 40 W-220 V. Which bulb will give more illuminance ?

A wire of length 5 m is stretched by 1 mm by a force of 1 N. What is the value of energy stored in the wire ?

One kg of copper is drawn into a wire of 1 mm diameter and a wire of 2 mm diameter. The resistance of the two wires will be in the ratio

• 2 : 1

• 1 : 2

• 16 : 1

• 4 : 1