Electrical Circuits
Overview
Flip one switch and a whole room of lights comes on, yet unplug one fairy light and the rest stay glowing. The difference is whether the components are wired in series, one after another, or in parallel, side by side. How you connect components decides the current through each, the voltage across each, and the total resistance of the circuit.
In this lesson you will read and draw circuit diagrams, use the rule that current is the same everywhere in a series circuit, add e.m.f.s and resistances in series, use the junction rule for currents in parallel, find the combined resistance of resistors in parallel, and explain why lights at home are wired in parallel. Every calculation shows the equation, the substitution and the answer with units.
Objectives
- [Core] Draw and interpret circuit diagrams containing cells, batteries, power supplies, switches, resistors (fixed and variable), heaters, lamps, motors, ammeters, voltmeters and fuses, and know how these components behave in the circuit
- [Core] Know that the current at every point in a series circuit is the same
- [Core] Know how to construct and use series and parallel circuits
- [Supplement] Draw and interpret circuit diagrams containing generators and light-emitting diodes (LEDs), and know how these components behave in the circuit
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Electrical Circuits. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- In a series circuit, the current is A. largest near the battery B. the same at every point C. used up by each component D. different in each component Answer: B
- Two 1.5 V cells are connected in series the same way round. The combined e.m.f. is A. 0.75 V B. 1.5 V C. 3.0 V D. 4.5 V Answer: C
- Resistors of 3 ohm and 6 ohm in series have a combined resistance of A. 2 ohm B. 4.5 ohm C. 9 ohm D. 18 ohm Answer: C
- Resistors of 4 ohm and 12 ohm in parallel have a combined resistance of A. 3 ohm B. 8 ohm C. 16 ohm D. 48 ohm Answer: A
- Lamps in a house are wired in parallel mainly so that A. they share the current B. each can be switched independently and shines at full brightness C. they use less energy D. one failing switches them all off Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Recommended Books
Practice Mock Questions
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