To Study Dependence of Current on Potential Difference (Class 10 Physics Practical)
To demonstrate that current in a conductor is directly proportional to potential difference and verify Ohm's law experimentally
TL;DR: To demonstrate that current in a conductor is directly proportional to potential difference and verify Ohm's law experimentally
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Aim: To demonstrate that current in a conductor is directly proportional to potential difference and verify Ohm's law experimentally
Materials Required
- Nichrome wire or resistor
- Ammeter
- Voltmeter
- Variable power supply or rheostat
- Battery
- Connecting wires
- Switch
- Graph paper
Theory
Ohm's law states that current through conductor is directly proportional to potential difference applied across it at constant temperature: I = V/R or V = IR. The relationship is linear and R is constant for ohmic conductors. This fundamental law governs electric circuits and helps predict circuit behavior.
Procedure
- Connect nichrome wire in series with ammeter and variable power supply
- Connect voltmeter in parallel across the nichrome wire
- Close switch with minimum voltage setting
- Record voltmeter reading and corresponding ammeter reading
- Increase voltage using power supply gradually in small steps
- Record ammeter and voltmeter readings for each voltage
- Take at least 6-8 readings for wide voltage range
- Plot graph with voltage on X-axis and current on Y-axis
- Verify linear relationship and calculate resistance from slope
Observation
Current increases as voltage increases. Relationship is linear and passes through origin. Resistance remains constant throughout experiment. Graph shows straight line confirming direct proportionality.
Result
Current is directly proportional to potential difference. V/I ratio remains constant confirming Ohm's law. Resistance of nichrome wire determined from graph slope.
Precautions
- Do not exceed maximum voltage of power supply
- Use appropriate meter ranges for all measurements
- Ensure wire does not heat excessively
- Connect voltmeter in parallel across conductor
- Connect ammeter in series with circuit
- Take readings at small voltage intervals for accuracy
Viva Questions
State Ohm's law.
Ohm's law states that the current through a conductor is directly proportional to the potential difference applied across it, provided temperature remains constant. Mathematically: V = IR or I = V/R.
What is an ohmic conductor?
An ohmic conductor is one that obeys Ohm's law with constant resistance over range of currents. Examples include nichrome wire and most metals at constant temperature.
Why must temperature remain constant in this experiment?
Temperature must remain constant because resistance of conductor changes with temperature. Heating of wire would change resistance and violate the proportionality.
What does graph slope represent in this experiment?
The slope of V-I graph (voltage divided by current) represents the resistance of the conductor.
What would happen if conductor was non-ohmic?
For non-ohmic conductor, V-I graph would be curved instead of straight line, and resistance would vary with applied voltage.
Why is it important to connect voltmeter in parallel?
Voltmeter must be in parallel to measure voltage across the conductor. If connected in series, it would change the circuit and give incorrect readings.
More Class 10 Physics Practicals
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- To Verify Ohm's Law
- To Find Resistance Using a Metre Bridge
- To Study the Laws of Reflection
- To Determine the Density of a Solid
- To Verify the Laws of Refraction (Glass Slab)
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