Current Electricity

The reading of the ammeter for a silicon diode in the given circuit is

• 13.5 mA

• 0 mA

• 15 mA

• 11.5 mA

Two batteries with e.m.f 12 V and 13 V are connected in parallel across a load resistor of 10Ω. The internal resistance of the two batteries are 1Ω and 2Ω respectively. The voltage across the load lies between :

• 11.7 V and 11.8 V

• 11.6 V and 11.7 V

• 11.5 V and 11.6 V

• 11.4 V and 11.5 V

In an a.c. circuit, the instantaneous e.m.f. and current are given by
e = 100 sin 30 t

$i = 20 \sin \left(30 t -\frac{\pi }{4}\right)$

In one cycle of a.c., the average power consumed by the circuit and the wattless current are, respectively

• 50,0

• 50,10

• $\frac{1000}{\sqrt{2}}, 10$

• $\frac{50}{\sqrt{2}},0$

On interchanging the resistances, the balance point of a meter bridge shifts to the left by 10 cm. The resistance of their series combination is 1 kΩ. How much was the resistance on the left slot before interchanging the resistances?

• 910Ω

• 990Ω

• 505Ω

• 550 Ω

In a potentiometer experiment, it is found that no current passes through the galvanometer when the
terminals of the cell are connected across 52 cm of the potentiometer wire. If the cell is shunted by a
resistance of 5Ω, a balance is found when the cell is connected across 40 cm of the wire. Find the internal
resistance of the cell.

• 2.5 Ω

• 1 Ω

• 1.5 Ω

• 2 Ω

A copper wire with a cross-section area of 2 x10^-6 m² has a free electron density equal to 5 x 10²² /cm³. If this wire carries a current of 16 A, the drift velocity of the electron is

• 1 m/s

• 0.1 m/s

• 0.01 m/s

• 0.001 m/s

The resistance of the tungsten wire in the light bulb, which is 120V/75 W and powered by a 120 V direct current supply, is

• 0.37 Ω

• 1.2 Ω

• 2.66 Ω

• 192 Ω

The value of the current I₁, I₂ and I₃ flowing through the circuit given below is

• I₁ = − 3A, I₂ = 2A, I₃ = − 1A

• I₁ = 2A, I₂ = − 3A, I₃ = − 1A

• I₁ = 3A, I₂ = − 1A, I₃ = − 2A

• I₁ = 1A, I₂ = − 3A, I₃ = − 2A

A silver wire has temperature coefficient of resistivity 4 x 10^-3 / °C and its resistance at 20°C is 10 Ω. Neglecting any change in dimensions due to the change in temperature, its resistance at 40°C is

• 0.8 Ω

• 1.8 Ω

• 9.2 Ω

• 10.8 Ω

If copper and silicon pieces are heated, the resistance of

• each will increase

• each will decrease

• copper will increase and silicon will decrease

• copper will decrease and silicon will increase