Using Kirchhoff's laws of current and voltage, find the current in 2Ω resistor in the given circuit.

Ans: 10A

A voltmeter coil has a resistance of 50 Ω and a resistor of 1.15 K Ω is connected in series. If can read potential differences up to 12 volts. If the same coil is used to construct an ammeter which can measure currents upto 2A, what should be the resistance of the shunt used?

Ans: 0.25Ω

The total length of the wire of a potentiometer is 10m. A potential gradient of 0.0015 V/cm is obtained when a steady current is passed through this wire, Calculate,

1. the distance of null point on connecting the standard cell of 1.018V
2. the unknown p.d. if the null point is obtained at a distance of 940 cm
3. the maximum p.d. which can be measured by this instrument

Ans: (i) 6.8 m (ii) 1.41 V (iii) 1.5 v 

A battery of 6V and internal resistance 0.5Ω is joined in parallel with another of 10V and internal resistance 1Ω. The combination sends a current through an external resistance of 12Ω. Find the current through each battery.

Ans: l₁ = 2.27A, l₂ = 2.86 A

The resistance of a galvanometer coil is 9.36Ω, and the current required for full scale deflection is 0.0224A. We want to convert this galvanometer to an ammeter reading 20A full scale. The only shunt available has a resistance of 0.025Ω. What resistance must be connected in series with the coil?

Ans: 12.94 Ω

A simple potentiometer circuit is set up as in the figure using a uniform wire AB, 1.0 m long, which has a resistance of 2Ω. The resistance of the 4V battery is negligible. If the variable resistor R was given a value of 2.4Ω what would be the length AC for zero galvanometer deflection?

Ans: 0.825 m

What must be the emf E in the circuit so that the current flowing through the 7Ω resistor is 1.80A? Each emf source has negligible internal resistance.

Ans: 8.6 V

A potentiometer is 10 m long. It has a resistance of 20 Q. It is connected in series with a battery of 3 V and a resistance of 10 Q. What is the potential gradient along with the wire?

 Ans: 0.2 V/m 

The resistance of the coil of a galvanometer is 9.36Ω and a current of 0.0224 A causes it to deflect full scale. The only shunt available has a resistance of 0.025Ω. What resistance must be connected in series with the coil to make it an ammeter of range 0 - 20A?

Ans: 12.94 Ω

A moving coil meter has a resistance of 25Ω and indicates full-scale deflection when a current of 4.0 mA flows through it. How could this meter be converted to a milliammeter having a full-scale deflection for a current of 50mA?

Ans: 2.14 Ω

The emf of a battery is balanced by a length 75 cm on a potentiometer wire and emf of a standard cell of 1.02 volt is balanced by a length 50 cm of it. Calculate the emf of the battery.

Ans: 1.53 V

Using Kirchhoff's rules in the circuit, find

1. the current in resistor R
2. the resistance R
3. the unknown emf E
4. If the circuit is broken at P, what is the current in resistor R?

Ans: 2A, 5Ω, 42V, 3.5A

An unknown resistance R₁ is connected in series with resistance 10 Ω. This combination is connected to one of the gaps of a meter bridge, while another resistance R₂ is connected to next gap. The balance point is obtained at 50 cm. Now, when 10 Ω resistance is removed, the balance point is 40cm. Find the value of R₁.

Ans: 20 Ω

A potentiometer is used to measure the internal resistance of a cell. When the cell in the secondary circuit is short circuited by 5 Ω resister, the null point is at 220 cm. Again, when the cell is shunted by 20 Ω resister, the null point is at 300 cm. What is the internal resistance of the cell?

Ans: 2.76 Ω

A galvanometer has a resistance of 10 Ω. It gives maximum deflection for a current of 50 mA. Find the shunt resistance to convert it into ammeter of range 2.5 A.

Ans: 0.2 Ω