Science: Series and Parallel Circuits Worksheet

Question 1

Define a series circuit and a parallel circuit in your own words.

Accepted Answer

A series circuit has components connected in a single path, so the same current flows through each part. A parallel circuit has components connected on separate branches, so current can travel along more than one path.

Question 2

A circuit has a 12 V battery and three resistors connected in series: 2 ohms, 3 ohms, and 5 ohms. Find the total resistance.

Accepted Answer

The total resistance is 10 ohms because resistances in series add directly: 2 + 3 + 5 = 10.

Question 3

Using the circuit from the previous problem, calculate the total current in the circuit.

Accepted Answer

The total current is 1.2 A because current equals voltage divided by resistance: 12 V divided by 10 ohms equals 1.2 A.

Question 4

In a series circuit, one bulb burns out. Describe what happens to the rest of the bulbs and explain why.

Accepted Answer

The rest of the bulbs go out because a series circuit has only one path for current. When one bulb burns out, the path is broken and current stops everywhere in the circuit.

Question 5

A parallel circuit contains two branches. One branch has a 6 ohm resistor and the other has a 3 ohm resistor. The source voltage is 12 V. Find the current in each branch.

Accepted Answer

The current in the 6 ohm branch is 2 A because 12 V divided by 6 ohms equals 2 A. The current in the 3 ohm branch is 4 A because 12 V divided by 3 ohms equals 4 A.

Question 6

For the parallel circuit in the previous problem, calculate the total current supplied by the battery.

Accepted Answer

The total current is 6 A because the branch currents add in a parallel circuit: 2 A + 4 A = 6 A.

Question 7

A student says that voltage is the same across each resistor in a series circuit. Explain whether this statement is correct.

Accepted Answer

The statement is not correct. In a series circuit, the current is the same through each resistor, but the voltage is divided among the resistors based on their resistance values.

Question 8

Three resistors of 4 ohms each are connected in parallel. Find the equivalent resistance.

Accepted Answer

The equivalent resistance is 4/3 ohms, or about 1.33 ohms. For three equal resistors in parallel, the equivalent resistance equals one resistor divided by the number of resistors: 4 divided by 3.

Question 9

A 9 V battery is connected to two resistors in series, 1 ohm and 2 ohms. Find the current and the voltage drop across each resistor.

Accepted Answer

The total resistance is 3 ohms, so the current is 3 A because 9 V divided by 3 ohms equals 3 A. The voltage drop across the 1 ohm resistor is 3 V, and the voltage drop across the 2 ohm resistor is 6 V.

Question 10

Explain why adding more branches to a parallel circuit usually decreases the total resistance.

Accepted Answer

Adding more branches gives current more paths to follow. More available paths make it easier for charge to move through the circuit, so the total resistance decreases.

Question 11

A 24 V source is connected to two resistors in parallel, 8 ohms and 12 ohms. Find the equivalent resistance.

Accepted Answer

The equivalent resistance is 4.8 ohms. Using 1/Req = 1/8 + 1/12 gives 1/Req = 5/24, so Req = 24/5 = 4.8 ohms.

Question 12

Using the circuit from the previous problem, calculate the total current from the source.

Accepted Answer

The total current is 5 A because current equals voltage divided by equivalent resistance: 24 V divided by 4.8 ohms equals 5 A.

Question 13

Compare the brightness of two identical bulbs connected in series with the brightness of the same two bulbs connected in parallel to the same battery.

Accepted Answer

The bulbs in parallel are brighter than the bulbs in series. In parallel, each bulb gets the full battery voltage, while in series the voltage is shared, so each bulb receives less power.

Question 14

A circuit has one 2 ohm resistor in series with a parallel combination of 6 ohms and 3 ohms. Find the total resistance of the circuit.

Accepted Answer

The parallel part has an equivalent resistance of 2 ohms because 1/Req = 1/6 + 1/3 = 1/2. Adding the series resistor gives a total resistance of 4 ohms.

Question 15

Describe one real-world situation where a parallel circuit is preferred over a series circuit, and explain why.

Accepted Answer

Household wiring is a real-world example where a parallel circuit is preferred. Each appliance receives the full source voltage and can operate independently, so one device turning off does not stop current to the others.

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Science: Series and Parallel Circuits

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