# SCERT Maharashtra Question Bank solutions for 12th Standard HSC Physics Maharashtra State Board 2021 chapter 9 - Current Electricity [Latest edition]

## Chapter 9: Current Electricity

MCQ’S

### SCERT Maharashtra Question Bank solutions for 12th Standard HSC Physics Maharashtra State Board 2021 Chapter 9 Current Electricity MCQ’S

#### 1 Mark Each

MCQ’S | Q 1

Kirchhoff’s second law (voltage law) is based on ______

• conservation of charge

• conservation of mass

• conservation of energy

• conservation of momentum

MCQ’S | Q 2

When unknown resistance is determined by meter bridge, the error due to contact resistance is minimised by ______

• connecting both the resistances only in one gap

• interchanging the position of known and unknown resistances

• using uniform wire

• obtaining the null point near the ends of the wire

MCQ’S | Q 3

The SI unit of the potential gradient is ______

• V/cm

• V-m

• V/m

• V-cm

MCQ’S | Q 4

The instrument which can measure terminal potential difference as well as electromotive force (emf) is ______

• Wheatstone’s meter bridge

• voltmeter

• potentiometer

• galvanometer

MCQ’S | Q 5

When the null point is obtained in the potentiometer, the current is drawn from the ______

• main battery

• cell battery

• both main and cell battery

• neither main nor cell battery

MCQ’S | Q 6

If the potential gradient of a wire decreases, then its length ______

• remains constant

• decreases

• increases

• none of the above

MCQ’S | Q 7

Four resistances 4 Ω,8Ω, XΩ and 12Ω are connected in a series to form Wheatstone’s network. If the network is balanced, the value of X is ______

• 24

• 18

• 12

• 8

### SCERT Maharashtra Question Bank solutions for 12th Standard HSC Physics Maharashtra State Board 2021 Chapter 9 Current Electricity Very Short Answer

#### 1 Mark Each

Very Short Answer | Q 1

State Kirchhoff’s first (current) law.

Very Short Answer | Q 2

State Kirchhoff’s second (voltage) law.

Very Short Answer | Q 3

What is the basis of Kirchhoff’s current law and voltage law?

Very Short Answer | Q 4

Are Kirchhoff’s laws applicable to both AC and DC circuits?

Very Short Answer | Q 5

Very Short Answer | Q 6

On what factors does the potential gradient of the wire depend?

Very Short Answer | Q 7

What is the SI unit of potential gradient?

Very Short Answer | Q 8

State any one use of a potentiometer.

Very Short Answer | Q 9

A voltmeter has a resistance of 100 Ω. What will be its reading when it is connected across a cell of emf 6 V and internal resistance 20 Ω?

Very Short Answer | Q 10

In a meter bridge, two unknown resistances R and S, when connected between the two gaps, give a null point is 60 cm from one end. What is the ratio of R and S?

### SCERT Maharashtra Question Bank solutions for 12th Standard HSC Physics Maharashtra State Board 2021 Chapter 9 Current Electricity Short Answer I

#### 2 Marks Each

Short Answer I | Q 1

What are the disadvantages of a potentiometer over a voltmeter?

Short Answer I | Q 2

Distinguish between a potentiometer and a voltmeter.

Short Answer I | Q 3

Distinguish between an ammeter and a voltmeter.

Short Answer I | Q 4

How do you calculate the shunt required to increase the length small n times?

Short Answer I | Q 5.1

Define: electrical circuit

Short Answer I | Q 5.2

Define: Junction

Short Answer I | Q 6

Calculate the value of the shunt resistance when connected across a galvanometer of resistance 18Ω will allow 1/10 th of the current to pass through the galvanometer.

Short Answer I | Q 7

Four resistances 6Ω, 6Ω, 6Ω and 18Ω form a Wheatstone bridge. Find the resistance which connected across the 18Ω resistance will balance the network.

Short Answer I | Q 8

The maximum safe voltage that can be measured using a galvanometer of resistance G is Vm . Find the resistance to be connected in series with the galvanometer so that it becomes a voltmeter of range nVm

### SCERT Maharashtra Question Bank solutions for 12th Standard HSC Physics Maharashtra State Board 2021 Chapter 9 Current Electricity Short Answer II

#### 3 Marks Each

Short Answer II | Q 1

Explain with a neat circuit diagram. How you will determine the unknown resistances using a meter bridge.

Short Answer II | Q 2

State any two sources of errors in the meter-bridge experiment. Explain how they can be minimized.

Short Answer II | Q 3

What is a potential gradient? How is it measured? Explain.

Short Answer II | Q 4

Describe how a potentiometer is used to compare the EMFs of two cells by connecting the cells individually.

Short Answer II | Q 5

A cell of e.m.f 1.5V and negligible internal resistance is connected in series with a potential meter of length 10 m and the total resistance of 20 Ω. What resistance should be introduced in the resistance box such that the potential drop across the potentiometer is one microvolt per cm of the wire?

Short Answer II | Q 6

In a meter bridge, the balance point is found to be at 39.5 cm from the end A when the resistor R is 12.5 Ω (right gap).

a) Determine the resistance of X (left gap).

b) Determine the balance point of the bridge if X and R are interchanged?

c) What happens if the galvanometer and cell are interchanged at the balance point of the bridge?

Short Answer II | Q 7

The emf of a standard cell is 1.5V and is balanced by a length of 300 cm of a potentiometer with a 10 m long wire. Find the percentage error in a voltmeter that balances at 350 cm when its reading is 1.8 V.

### SCERT Maharashtra Question Bank solutions for 12th Standard HSC Physics Maharashtra State Board 2021 Chapter 9 Current Electricity Long Answer

#### 4 Marks Each

Describe with the help of a neat circuit diagram how you will determine the internal resistance of a cell by using a potentiometer. Derive the necessary formula.

Describe how a potentiometer is used to compare the emf's of two cells by the combination method.

State the uses of a potentiometer.

Why is a potentiometer preferred over a voltmeter for measuring emf?

## SCERT Maharashtra Question Bank solutions for 12th Standard HSC Physics Maharashtra State Board 2021 chapter 9 - Current Electricity

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Concepts covered in 12th Standard HSC Physics Maharashtra State Board 2021 chapter 9 Current Electricity are Current Electricity, Kirchhoff’s Laws of Electrical Network, Wheatstone Bridge, Potentiometer, Galvanometer.

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