Determination Of Resistance Using Meter Bridge

APPARATUS REQUIRED: 

• Meter bridge 
• One-way key 
• Galvanometer 
• Resistance box 
• Jockey 
• Leclanche cell 
• Connecting wires

THEORY:

The meter bridge is based on the principle of a Wheatstone bridge. The resistance of a wire is determined by finding the null point, where the bridge is balanced, and the galvanometer shows zero deflection.

PROCESS:

1. Set up the meter bridge with a one-way key and galvanometer. 
2. Connect the given wire to the meter bridge and adjust its length. 
3. Insert a known resistance in the resistance box. 
4. Connect the Leclanche cell to the circuit. 
5. Slide the jockey along the wire, find the null point (zero deflection) on the galvanometer. 
6. Measure the lengths of the wire on either side of the null point. 
7. Repeat the experiment with different known resistances.

OBSERVATIONS:

Length of wire on one side of the null point: 40 cm

Length of wire on the other side of the null point: 60 cm

OBSERVATION TABLE:

                                 

Known Resistance (R1)	Length (L1)	Length (L2)
20 ohms	40 cm	60 cm

CALCULATION:

Calculate the resistance of the given wire using the formula \( R = R_1 \frac{L_1}{L_2} \).

RESULTS:

The resistance of the given wire is 30 ohms.

PRECAUTIONS: 

1. Ensure tight connections and minimal contact resistance. 
2. Avoid parallax error while taking readings. 
3. Make sure the jockey is not short-circuiting the wire. 
4. Allow the apparatus to stabilize before taking readings.