To Verify Ohm's Law (Class 10 Physics Practical)
To verify that the ratio of potential difference to current (resistance) remains constant for a given conductor.
TL;DR: To verify that the ratio of potential difference to current (resistance) remains constant for a given conductor.
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
Aim: To verify that the ratio of potential difference to current (resistance) remains constant for a given conductor.
Materials Required
- Ammeter (0-1 A)
- Voltmeter (0-5 V)
- Nichrome wire
- Variable power supply
- Rheostat
- Key/switch
- Connecting wires
- Stand and clamps
Theory
Ohm's Law states that the current flowing through a conductor is directly proportional to the potential difference across it, provided temperature remains constant. This is expressed as V = IR or R = V/I, where R is resistance and remains constant for a given conductor at constant temperature.
Procedure
- Set up the circuit with the nichrome wire as the conductor, ammeter in series, and voltmeter in parallel across the wire
- Adjust the variable power supply to its minimum value
- Close the key and record the voltmeter and ammeter readings
- Gradually increase the power supply voltage in small steps
- For each voltage value, record the corresponding current from the ammeter
- Take at least 6-7 sets of V-I readings across the voltage range
- Calculate resistance R = V/I for each set of readings
- Plot a V-I graph; it should be a straight line passing through origin
Observation
As the potential difference across the nichrome wire is increased, the current also increases proportionally. The ratio V/I remains approximately constant for all readings, demonstrating that resistance is independent of applied voltage.
Result
Ohm's Law is verified. The resistance of the nichrome wire remains constant at approximately [value] Ohm across different voltage and current values.
Precautions
- Ensure all connections are tight and secure
- Never exceed the maximum reading of ammeter and voltmeter
- Do not keep the circuit closed for long periods to avoid heating of the wire
- Use appropriate meter ranges and take initial reading at lowest voltage
Viva Questions
State Ohm's Law.
Ohm's Law states that V = IR, or the current through a conductor is proportional to the potential difference, at constant temperature.
Why is the ammeter connected in series?
The ammeter measures current, and to measure the actual current through the conductor, it must be in series with it.
Why should the wire not be heated excessively?
Heat increases the resistance of the conductor, making the V/I ratio non-constant and violating Ohm's Law conditions.
What does the slope of the V-I graph represent?
The slope of the V-I graph represents the resistance of the conductor.
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- To Determine the Density of a Solid
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