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Electricity - Series circuits and circuit diagrams

Grade 5IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

A series circuit is a circuit where all components are connected in a single loop, providing only one path for the electric current II to flow.

Circuit diagrams use standard symbols to represent components: a cell is shown as a long and short parallel line \dashv \vdash, a bulb is a circle with an 'X' \otimes, and a switch is shown as two dots connected or disconnected by a line.

The current II, measured in Amperes (AA), is the same at every point in a series circuit. If I=0.5 AI = 0.5\ A at the battery, it is 0.5 A0.5\ A at the bulb.

If any component in a series circuit breaks or is disconnected, the entire circuit is 'broken' and the current II stops flowing, meaning no components will work.

Adding more cells in series increases the total voltage VV, which usually makes bulbs shine brighter. Conversely, adding more bulbs in series increases resistance, making the bulbs dimmer.

Voltage VV, also called potential difference, is measured in Volts (VV) using a voltmeter connected in parallel, though the circuit itself is series.

📐Formulae

Itotal=I1=I2=I3I_{total} = I_1 = I_2 = I_3

Vtotal=V1+V2+V3V_{total} = V_1 + V_2 + V_3

Vbattery=Vcell1+Vcell2V_{battery} = V_{cell1} + V_{cell2}

💡Examples

Problem 1:

A series circuit contains two 1.5 V1.5\ V cells and one bulb. What is the total voltage VtotalV_{total} supplied to the bulb?

Solution:

Vtotal=1.5 V+1.5 V=3.0 VV_{total} = 1.5\ V + 1.5\ V = 3.0\ V

Explanation:

In a series circuit, the voltages of the cells are added together to find the total voltage supplied to the components.

Problem 2:

An ammeter placed next to the battery in a series circuit reads 0.2 A0.2\ A. What would another ammeter read if it was placed between two bulbs further down the same circuit?

Solution:

I=0.2 AI = 0.2\ A

Explanation:

In a series circuit, the current II is the same at all points because there is only one path for the electricity to follow.

Problem 3:

If a series circuit has three bulbs and one bulb 'blows' (the filament breaks), what happens to the other two bulbs?

Solution:

The other two bulbs will turn off.

Explanation:

A 'blown' bulb creates a gap in the circuit. Since there is only one path in a series circuit, the break stops the flow of current II entirely.

Series circuits and circuit diagrams Revision - Grade 5 Science IGCSE