Current Electricity

In the circuit, R₁ = R₂. The value of E and R₁ are (E - EMF, R₁ - resistance)

• 180 V, 60 Ω

• 120 V, 60 Ω

• 180 V, 10 Ω

• 120 V, 10 Ω

Masses of three wires of copper are in the ratio of 1 : 3 : 5 and their lengths are in the ratio of 5 : 3 : 1. The ratio of their electrical resistances is

• 1 : 3 : 5

• 5 : 3 : 1

• 1 : 15 : 125

• 125 : 15 : 1

Two identical circular coils A and B are kept on a horizontal tube side by side without touching each other. If the current in the coil A increases with time, in response, the coil B

• is attracted by A

• remains stationary

• is repelled

• rotates

In the diagram, I₁, I₂ are the strength of the currents in the loop and straight conductors respectively. OA = AB = R. The net magnetic field at the centre O is zero. Then the ratio of the currents in the loop and the straight conductors is

• $\mathrm{\pi }$

• $2\mathrm{\pi }$

• $\frac{1}{\mathrm{\pi }}$

• $\frac{1}{2\mathrm{\pi }}$

In the circuit diagram, heat produces in R, 2R and 1.5 R are in the ratio of

• 4 : 2 : 3

• 8 : 4 : 27

• 2 : 4 : 3

• 27 : 8 : 4

A carbon film resistor has colour code Green, Black, Violet, Gold. The value of the resistor is

• 50 MΩ

• 500 MΩ

• 500 ± 5% MΩ

• 500 ± 10% MΩ

Two resistors of resistances 2 Ω and 6 Ω are connected in parallel. This combination is then connected to a battery of emf 2 V and internal resistance 0.5 Ω. What is the current flowing through the battery ?

• 4 A

• $\frac{4}{3} \mathrm{A}$

• $\frac{4}{17} \mathrm{A}$

• 1 A

The equivalent resistance of two resistors connected in series is 6 Ω and their parallel equivalent resistance is  $\frac{4}{3} \mathrm{\Omega }$. What are the values of resistances ?

• 4 Ω, 6 Ω

• 8 Ω, 1 Ω

• 4 Ω, 2 Ω

• 6 Ω, 2 Ω

In a potentiometer experiment of a cell of emf 1.25 V gives balancing length of 30 cm. If the cell is replaced by another cell, balancing length of 30 cm. If the cell is replaced by another cell, balancing length is found to be 40 cm. What is the emf of second cell ?

• ≈ 1.57 V

• ≈ 1.67 V

• ≈ 1.47 V

• ≈ 1.37 V

The circuit has two oppositely connected ideal diodes in parallel. What is the current flowing in the circuit ?

• 2.31 A

• 1.71 A

• 1.33 A

• 2.0 A