To Verify Laws of Series Resistances (Class 10 Physics Practical)
To verify the laws of series resistances and demonstrate that total resistance in series equals sum of individual resistances
TL;DR: To verify the laws of series resistances and demonstrate that total resistance in series equals sum of individual resistances
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Aim: To verify the laws of series resistances and demonstrate that total resistance in series equals sum of individual resistances
Materials Required
- Three resistors of known values
- Ammeter
- Voltmeter
- Rheostat
- Battery and switch
- Connecting wires
- Plugged key
Theory
In series circuits, resistors are connected end to end and same current flows through all resistors. The voltage divides among resistors proportional to their resistance. Total resistance R_total = R1 + R2 + R3. The voltage across series resistors follows Ohm's law: V = IR. This arrangement is used in applications requiring controlled voltage drop.
Procedure
- Connect three resistors in series between battery terminals through ammeter and switch
- Connect voltmeter across the first resistor
- Close the switch and note ammeter reading and voltmeter reading
- Move voltmeter to measure voltage across second resistor, note readings
- Move voltmeter to measure voltage across third resistor, note readings
- Measure total voltage across all three resistors using voltmeter
- Vary the current using rheostat and repeat measurements
- Calculate individual resistances using Ohm's law: R = V/I
- Compare total measured resistance with sum of individual resistances
Observation
Same current flows through all three resistors (ammeter reading constant). Voltages add up: V_total = V1 + V2 + V3. Larger resistors have larger voltage drop. Total voltage equals sum of individual voltages. Current remains constant throughout series circuit.
Result
Law of series resistances verified: R_total = R1 + R2 + R3. Voltage distribution is proportional to resistance values. Equivalent resistance of series combination determined.
Precautions
- Check ammeter range before connecting
- Use voltmeter of appropriate range for measurements
- Connect ammeter in series with circuit
- Connect voltmeter in parallel across resistor
- Keep rheostat at maximum resistance before closing switch
Viva Questions
What is series connection of resistors?
Series connection is when resistors are connected end to end in a single path so same current flows through all of them.
How do voltages behave in series circuit?
In series circuit, total voltage equals sum of individual voltages across each resistor. Voltage divides proportional to resistance values.
What is equivalent resistance in series?
Equivalent resistance in series is R_eq = R1 + R2 + R3 + ... The total resistance is greater than any individual resistance.
Why is ammeter connected in series?
Ammeter is connected in series because it measures current flowing through circuit and must have minimal resistance so it does not affect circuit.
What happens if one resistor burns out in series circuit?
If one resistor burns out in series circuit, the entire circuit breaks and no current flows as the series path is interrupted.
Compare series with parallel resistors.
In series, same current flows through all and voltage divides. In parallel, voltage remains same across all and current divides. Series has higher total resistance while parallel has lower.
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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