A potentiometer wire of length 10 m and resistance 20 Ω is connected in series with a 15 V battery and an external resistance 40 Ω. A secondary cell of emf E in the secondary circuit is balanced by 240 cm long potentiometer wire. The emf E of the cell is

• 2.4 V

• 1.2 V

• 2.0 V

• 3 V

In the following circuit, the current flowing through 1 kΩ resistor is

• 0 mA

• 5 mA

• 10 mA

• 15 mA

93.

The current I through 10 Ω resistor in the circuit given below is

           

• 50 mA

• 20 mA

• 40 mA

• 80 mA

In the figure shown below, the terminal voltage across E₂ is

• 12 V

• 12.66 V

• 11.34 V

• 11.66 V

The drift velocity of the electrons in a copper wire of length 2 m under the application of a potential difference of 220 V is 0.5 ms^-1. Their mobility (in m²V^-1s^-1)

• 2.5 × 10^-3 

• 2.5 × 10^-2

• 5 × 10²

• 5 × 10^-3

When two resistances R₁ and R₂ are connected in series, they consume 12 W power. When they are connected in parallel, they consume 50 W power. What the ratio of the powers of R₁ and R₂ ?

• 1/4

• 4

• 3/2

• 3

In the circuit shown, if the resistance 5 Ω develops a heat of 42 J per second, heat developed in 2 Ω must be about (in Js^-1)

• 25

• 20

• 30

• 35

When a Daniel cell is connected in the secondary circuit of a potentiometer, the balancing length is found to be 540 cm. If the balancing length becomes 500 cm when the cell is short circuited with 1 Ω, the internal of the cell is

• 0.08 Ω

• 0.04 Ω

• 1.0 Ω

• 1.08 Ω

A resistor 30 Ω, inductor of reactance 10 Ω and capacitor of reactance 10 Ω are connected in series to an AC voltage source $\mathrm{e} = 300\sqrt{2} \sin \left(\mathrm{\omega t}\right)$. The current in the circuit is

• $10\sqrt{2} \mathrm{A}$

• 10 A

• $30\sqrt{11} \mathrm{A}$

• $30/ \sqrt{11} \mathrm{A}$

The resistance of a wire at room temperature 30˜C is found to be 10 Ω. Now to increase the resistance by 10%, the temperature of the wire must be [The  temperature coefficient of resistance of the material of the wire is 0.002/°C]

• 36°C

• 83°C

• 63°C

• 33°C