Current Electricity - Practice Questions- Question bank

 

CURRENT ELECTRICITY QUESTION BANK

 

          Q.1. Define the following terms

1.   Potentiometer

2.   Potential gradient

       

         Q.2. State and explain

1.   Kirchhoff’s current law/junction law

2.   Kirchhoff’s voltage law

3.   Potentiometer principle

           

         Q.3. What are the uses of a potentiometer?

       

          Q.4. Distinguish between a potentiometer and a voltmeter.

     

          Q.5. What are the disadvantages of a potentiometer?

    

          Q.6. What are the advantages of a potentiometer over voltmeter?

     

          Q.7. Describe how a potentiometer is used to compare the emf of                        two cells by connecting the cells individually.

        

          Q.8. Describe how a potentiometer is used to compare the emf of                        two cells by combination method.

      

          Q.9. What is sum method? Draw the symbolic diagram.

      

          Q.10. What is difference method? Draw the symbolic diagram.

        

          Q.11. 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.

        

           Q.12. Obtain the balancing condition in case of a Wheatstone’s                            network.

     

            Q.13. Explain with neat circuit diagram, how you will determine                           the unknown resistance by using a meter-bridge.

        

            Q.14. What is potential gradient? How is it measured? Explain.

OR

            Q.15. State and explain principle of potentiometer.

     

            Q.16. What are the advantages of potentiometer over voltmeter?

      

            Q.17. What are the uses of potentiometer?

     

            Q.18. What are the applications of potentiometer?

 

 

 

 

Kirchhoff's Voltage Law

 Kiichhoff's Voltage Law

Question : State and Explain Kirchhoff's Voltage Law with its sign conventions.

Wheatstone - Bridge

 Question : Explain the working of Wheatstone Bridge 

Resistor color coding

 

Resistance color coding

Resistors are essential components in electronic circuits, they control the flow of electric current.

To identify their resistance value, a color coding system is used.

Why Use Color Coding?

Resistors are small, and printing numerical values on them and reading those values is difficult. Instead, manufacturers use colored bands to represent values, to ensure quick identification without using any special equipment.

The Resistor Color Code System

Resistors typically have four, five, or six color bands. Each color corresponds to a numerical value, a multiplier, and sometimes a tolerance.

Standard Four-Band System

• First and Second Bands: Represent the first two digits of the resistance value.
• Third Band: Acts as the multiplier (10 raised to a power).
• Fourth Band: Indicates tolerance (accuracy of the resistor value).

Resistors have colored bands that represent numbers.

To find the resistance, you read the first two colored bands as numbers. The third band tells you how many zeros to add.

How to remember color code?

"Black Bears Roar Over Yellow Grass. Brave Violet Giants Walk!"

Kirchhoffs Current Law/Junction Law

 

Kirchhoff’s Current Law

Question: State and explain Kirchhoff’s Current Law

OR

State and explain Kirchhoff’s First Law

OR

State and explain Junction Law

 

Statement: “At junction the algebraic sum of the currents is zero.”

Sign Conventions:

At the junction

1.  Arriving current considered as positive

2.  Leaving current is considered as negative

Explanation:

At the junction the arriving currents are I₁, I₃ and I₆ and

The leaving currents are I₂, I₄ and I₅

According to KCL

I₁-I₂+I₃-I₄-I₅+I₆ = 0

I₁+I₃+I₆ = I₂+I₄+I₅

Thus, the total current flowing towards the junction is equal to the total current flowing away from the junction.

Difference between voltmeter and ammeter

 

Voltmeter Vs Ammeter

Question: Distinguish between voltmeter and ammeter

OR

   Give the differences between voltmeter and ammeter

Sr No.	VOLTMETER	AMMETER
1	It is used to measure voltage	It is used to measure current
2	It is connected in parallel	It is connected in series
3	It is a MCG with infinite/very high resistance	It is a MCG with zero/low resistance
4	Larger its resistance , greater will be the potential difference measured.	Smaller the shunt, greater will be the current measured.
5	Resistance of voltmeter is Rv = G+ X        = G.nV	Resistance of ammeter is      RA= S.G/S+G          = G/n

 

Specific Resistance - Resistivity

SPECIFIC RESISTANCE 

(RESISTIVITYρ)

Resistivity is a property of material.

Definition: Resistance per unit length per unit area of cross section of material of conductor is called specific resistance of the material.

The resistance of the given conductor depends on

1.  Nature of material of conductor

2.  Area of its cross section

3.  Its length

The resistance (R) of a conductor of uniform cross section is –

1.  Directly proportional to its length (l)

2.  Inversely proportional to its area of cross section  (A)

Thus the resistance is

                                R  l/A

                                R = ρl/A

Where ρ is the specific resistance also called resistivity

Therefore,

ρ = RA/l

The SI unit of ρ is ohm-metre (Ωm)