Experimet- 10 :- Verification Of Ohm's :Law , Kirchhoff's Current Law (KCL) And Kirchhoff's Voltage Law (KVL)

Aim: To verify ohm’s law 

Material required : A resistor of about 5 Ω, an ammeter ( 0 - 3 A), a voltmeter (0 - 10 V), four dry cells of 1.5 V each with a cell holder (or a battery eliminator), a plug key, connecting wires, and a piece of sand paper. 

Precautions : All the electrical connections must be neat and tight.  Voltmeter and Ammeter must be of proper range.  The key should be inserted only while taking readings. 

Procedure : 

1. Draw the circuit diagram as shown above. 
2. Arrange the apparatus as per the circuit diagram. 
3. Clean the ends of the connecting wires with sand paper and make them shiny. 
4. Make the connections as per circuit diagram. All connections must be neat and tight. Take care to connect the ammeter and voltmeter with their correct polarity. (+ve to +ve and -ve to - ve). 
5. Determine the zero error and least count of the ammeter and voltmeter and record them. 
6. Adjust the rheostat to pass a low current. 
7. Insert the key K and slide the rheostat contact to see whether the ammeter and voltmeter are showing deflections properly. 
8. Adjust the rheostat to get a small deflection in ammeter and voltmeter. 
9. Record the readings of the ammeter and voltmeter. 
10. Take atleast six sets of readings by adjusting the rheostat gradually. 
11. Plot a graph with V along x-axis and I along y-axis. 
12. The graph will be a straight line which verifies Ohm's law. 
13. Determine the slope of the V-I graph. The reciprocal of the slope gives resistance of the wire.

Observations:

 Range of the given ammeter=.................... A. 

 Least count of the given ammeter = ..................... A. 

 Range of the given voltmeter = .....................V. 

 Least count of the given voltmeter = .....................V. 

 Mean value of V/I from observations, R = .......... Ω. 

Observation from graph:

 Slope of I vs V graph = ........... 

 R from graph = 1/ slope = .............. Ω

Kirchhoff's Current Law (KCL) Experiment

Theory

Kirchhoff's Current Law states that the algebraic sum of currents at any junction (or node) in a circuit is zero. This means the sum of currents entering a node must equal the sum of currents leaving that node. This law is based on the conservation of charge, as charge cannot be created or destroyed.  

Procedure

1. Obtain a suitable circuit diagram with at least one junction where three or more branches meet.

2. Connect the circuit on the trainer kit as per the diagram, using resistors and a DC power supply.

3. Adjust the input voltage to a desired value using the adjuster.

4. Connect ammeters in series with each branch leading to or from the junction.

5. Record the current readings for each branch. Note which currents are entering the junction and which are leaving.

6. Repeat the procedure for different input voltage settings to obtain multiple sets of observations.  

   
   
   

7. Verify KCL by checking if the sum of currents entering the junction equals the sum of currents leaving the junction for each set of readings.

   • $I_{entering}=I_{leaving}$

   • Example: If I1​ and I2​ enter a node and I3​ leaves, then $I_1+I_2=I_3$.

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Kirchhoff's Voltage Law (KVL) Experiment

Theory

Kirchhoff's Voltage Law states that the algebraic sum of all potential drops in a closed loop (or mesh) of an electric circuit is equal to the algebraic sum of all electromotive forces (EMFs) in that same loop. In simpler terms, the sum of voltage drops across resistors in a closed loop equals the total source voltage in that loop. This law is based on the conservation of energy. 

Procedure

1. Obtain a suitable circuit diagram containing at least one closed loop with multiple components (e.g., resistors and a voltage source).

2. Connect the circuit on the trainer kit as per the diagram.

3. Adjust the input voltage to a desired value.

4. Connect voltmeters in parallel across each component (resistors and voltage sources) within the chosen loop.

5. Record the voltage readings across each component.

6. Repeat the procedure for different input voltage settings. 

   
   
   

7. Verify KVL by checking if the sum of voltage drops across the resistors equals the total source voltage in the loop.

• $V_{source}=V_{R1}+V_{R2}+...+V_{Rn}$

• Example: If a loop has a source VS​ and resistors R1​, R2​, and R3​, then $V_S=V_{R1}+V_{R2}+V_{R3}$.

Conclusion