SCERT Maharashtra solutions for Physics [English] 12 Standard HSC chapter 9 - Current Electricity [Latest edition]

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

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

The SI unit of the potential gradient is ______  

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

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

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

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 ______.

State Kirchhoff’s first (current) law.

State Kirchhoff’s second (voltage) law.

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

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

Define potential gradient of the potentiometer wire.

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

What is the SI unit of potential gradient?

State any one use of a potentiometer.

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? 

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? 

What are the disadvantages of a potentiometer over a voltmeter?

Distinguish between a potentiometer and a voltmeter.

Distinguish between an ammeter and a voltmeter.

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

Define: electrical circuit 

Define: Junction

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. 

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

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

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

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

How is potential gradient measured? Explain.

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

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?  

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?

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.  

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?