Measurement of Current in a Series Circuit and Parallel Circuit

The Series and Parallel Current Experiment is designed to study how electric current behaves in different circuit configurations. In a series circuit, the current remains the same through all resistors because there is only one path for electron flow, while the total resistance increases as resistors are added. In a parallel circuit, the same voltage is applied across each branch, but the current splits according to the resistance of each branch, and the total current is the sum of all branch currents.Theory

Series Circuit: In series connection, there is only one path for current.

Total resistance:

𝑅 𝑡 𝑜 𝑡 𝑎 𝑙 = 𝑅 1 + 𝑅 2 + 𝑅 3 R total ​

=R 1 ​

+R 2 ​

+R 3 ​

Current:

𝐼 = 𝑉 𝑅 𝑡 𝑜 𝑡 𝑎 𝑙 I= R total ​

V ​

Same current flows through each resistor.

Parallel Circuit: In parallel connection, voltage across each branch is the same.

Equivalent resistance:

1 𝑅 𝑒 𝑞 = 1 𝑅 1 + 1 𝑅 2 + 1 𝑅 3 R eq

1

= R 1

1

+ R 2 ​

1 + R 3 1 ​

Branch currents:

𝐼 𝑛 = 𝑉 𝑅 𝑛 I n = R n V ​

Total current:

𝐼 𝑡 𝑜 𝑡 𝑎 𝑙 = 𝐼 1 + 𝐼 2 + 𝐼 3 I total =I 1 +I 2 +I 3

To verify that in a series circuit the current remains the same through all components.

To verify that in a parallel circuit the total current equals the sum of branch currents.

To compare experimental results with Ohm’s law.

DC power supply / Battery (6–12 V)

3 Resistors (e.g., 10 Ω, 22 Ω, 33 Ω)

Ammeter (or multimeter)

Voltmeter

Connecting wires, breadboard, and switch

Part A: Series Circuit

Connect the battery, switch, ammeter, and three resistors in series.

Close the switch and note current 𝐼 I.

Record supply voltage 𝑉 V.

Change resistor combinations (e.g., use only one, then two, then three resistors) and repeat.

Part B: Parallel Circuit

Connect three resistors in parallel across the battery.

Place ammeter in each branch (one at a time if only one is available).

Note down branch currents 𝐼 1 , 𝐼 2 , 𝐼 3 I 1 ​

,I 2 ​

,I 3 ​

and source current 𝐼 𝑡 𝑜 𝑡 𝑎 𝑙 I total.Repeat with different resistor combinations.

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