Physics Lab Experiments and Activities Manual

1. Ohm’s Law (V–I Relationship)

Aim

To verify Ohm’s Law and determine the resistance of a metallic conductor.

Apparatus

Battery, ammeter, voltmeter, rheostat, key, and resistance wire.

Theory

Ohm’s Law states that at a constant temperature, the current is directly proportional to the potential difference: V = IR.

Procedure

• Connect the circuit (ammeter in series, voltmeter in parallel).
• Adjust the current using the rheostat.
• Record the V and I readings.
• Plot a graph of V versus I.

Observation

A straight-line graph passing through the origin.

Result

Ohm’s Law is verified. Resistance R = V/I (slope of the graph).

2. Parallel Combination of Resistances

Aim

To verify the law of parallel combination using a meter bridge.

Theory

1/Rp = 1/R1 + 1/R2

Result

The equivalent resistance is less than the smallest individual resistance.

3. Resistance of Galvanometer (Half Deflection)

Aim

To determine the resistance of a galvanometer.

Theory

When deflection becomes half using shunt resistance S: G = S / (n − 1).

Result

Galvanometer resistance successfully calculated.

4. Resistance of Given Wire (Meter Bridge)

Formula

X = R × l / (100 − l)

Result

Resistance of the given wire determined.

5. Series Combination of Resistances

Theory

Rs = R1 + R2 + R3

Result

Total resistance equals the sum of individual resistances.

Section A: Activities

1. Household Circuit

Components: Fuse, switch, bulb, and power supply.

Important Points:

• Fuse and switch must be in the live wire.
• Bulb is connected in series.
• Reason: For safety and control.

2. Suitable Combination of Resistors

• Series: Increases total resistance.
• Parallel: Decreases total resistance.
• Verification: Using a multimeter.

Section B: Activities

1. Check Component Using Multimeter

Method: Set multimeter to resistance mode and check for continuity.

Result: Reading indicates a working component; no reading indicates a faulty component.

2. Concave Mirror Image Formation

3. Convex Lens Image

4. Lateral Displacement (Glass Slab)

Result: The emergent ray is parallel to the incident ray but shifted sideways.

Section B: Experiment

Focal Length of Concave Lens Using Convex Lens

Formula: 1/f = 1/v − 1/u

Result: Focal length determined.

Important Viva Questions

• Q: What is Ohm’s Law? A: V = IR.
• Q: Ammeter connection? A: Series.
• Q: Voltmeter connection? A: Parallel.
• Q: Fuse purpose? A: Safety device.
• Q: Series vs Parallel difference? A: Series has the same current; parallel has the same voltage.