Current Electricity

A potentiometer wire of length L and a resistance r are connected in series with battery of e.m.f. E_o and a resistance r₁. An unknown e.m.f is balanced at a length l of the potentiometer wire. The e.m.f E will be given by

A square loop, carrying a steady current I, is placed in a horizontal plane near a long straight conductor carrying a steady current I₁ at a distance d from the conductor as shown in the figure. The loop will experience

• a net repulsive force away from the conductor

• a net torque acting upward perpendicular to the horizontal plane

• a net torque acting downward normal to the horizontal plane

• a net torque acting downward normal to the horizontal plane

In the circuit shown in the figure, if potential at point A is taken to be zero,the potential at point B is

• -1V

• +2 V

• -2 V

• -2 V

In the given circuit the reading of voltmeter V₁ and V₂ are 300 V each. The reading to the voltmeter V₃ and ammeter A are respectively

• 150 V, 2.2 A

• 220 V , 2.2 A

• 220 V, 2.0 A

• 220 V, 2.0 A

Consider the following two statements

A) Kirchhoff junction law follows from the conservation of charge.

B) Kirchhoff's loop law follows from the conservation of energy

Which of the following is correct?

• Both (A) and (B) are wrong

• (A) Is correct and (B) is wrong

• (A) is wrong and (B) is correct

• (A) is wrong and (B) is correct

The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be

• 90

• 10

• 1.25

• 1.25

A current  of 3 A flows through the 2 Ω resistor shown in the circuit. The power dissiated in the 5 Ω resistor is 

diagram

• 4 W

• 2 W

• 1 W

• 1 W

A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively

• 1.2 times, 1.1 times

• 1.21 times, same

• both remain the same

• both remain the same

The total power dissipated in watts in the circuit shown here is:

• 16

• 40

• 54

• 54

The resistance of an ammeter is 13 Ω  and its scale is graduated for a current up to 100 A. After an additional shunt has been connected to this ammeter it becomes possible to measure currents up to 750 A by this meter. The value of shunt resistance is.

• 20 Ω

• 2 Ω

• 0.2 Ω

• 0.2 Ω