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Learning outcomes for this UNIT:
Learning outcomes for this UNIT:
By the end of the topic, learners will be able to:
• Identify, describe, and draw simple series and parallel circuit diagrams.
• Explain that the total voltage in a series circuit is equal to the sum of the voltages of individual cells in the circuit
• State that voltage is measured with a voltmeter
• Explain that voltmeters are always connected in parallel because they have a high resistance
• Explain that the brightness of a light bulb increases as more cells are connected in series.
• Explain that the total voltage across the battery is equal to the sum of the voltages across each of the resistors in a series circuit
• Explain that a resistor with high resistance will have a higher voltage across it
• Explain that a resistor with a lower resistance will have a lower voltage across it
• State that the current is the same when measured at any point in a series circuit
• State that current is measured using an ammeter
• Explain that ammeters are always connected in series because they have a low resistance
• Explain that the current in a circuit decreases with every resistor added in a series circuit.
• Explain that, when cells of the same voltage are connected in parallel, the voltage across each cell is the same as the voltage for one cell on its own
• Explain that the brightness of a light bulb does not change as more cells are connected in parallel.
• Explain that the voltage is the same across each resistor that is connected in parallel in a circuit
• Explain that the total current through the battery is equal to the sum of the currents through the resistors in parallel
• The total current in the circuit increases as more resistors are added in parallel.
• Explain that the lighting system in homes is usually connected in parallel
• Explain why the lighting system in homes is usually connected in parallel
• Explain that resistors are designed to have accurate resistance to control the current strength.
SERIES CIRCUITS
SERIES CIRCUITS
(a) For cells connected in series their voltages (potential differences) add up.
(b) Resistors can also be connected in series.
(c) In a series circuit, the electric current has only one path to follow.
(d) The resistor with higher resistance has a higher voltage of the total voltage in the circuit.
Complete this activity in your books and upload a picture on Google Classroom. A link will be opened named Classwork 1 Series and Parallel Circuits
Use the diagram above to answer some of the questions that follow:
1. What is the reading in the voltmeter of diagram 1?
2. What is the voltage in the resistors in diagram 1?
3. What is the voltage of the battery in diagram 2?
4. Discuss why the readings in the two bulbs are the same.
5. What is the relationship between the reading in each bulb of diagram 2 and that of the battery?
6. What is the total voltage in diagram 3?
7. Which resistor has the highest voltage?
8. Discuss why the resistor you identified has the highest voltage?
9. What is the relationship between voltage and resistance?
10.If all resistors in diagram 3 had the same resistance, how would that affect the voltage in each resistor?
Parallel Circuits
Parallel Circuits
(a) Cells of the same voltage connected in parallel produce a voltage equivalent to that of one cell.
(b) Cells in parallel are connected positive to positive and negative to negative whereas series cells are connected end to end (negative end to positive end).
(c) Connecting resistors in parallel reduces the resistance, such that the more the resistors the less the resistance.
(d)Parallel connections are used in our households.
(e) The higher the resistance, the smaller the current, and vice versa.
(f) For parallel resistors voltage is the same across each resistor.
(g) Parallel resistors split or divide the current at each junction. (Kirchhoff’s law)
Complete this activity in your books and upload a picture on Google Classroom. A link will be opened named Classwork 2 Series and Parallel Circuits.
Use the diagram to answer some of the questions that follow:
1. How are cells in series connected compared to cells in parallel?
2. What are the advantages and disadvantages of connecting cells in parallel?
3. Looking at the diagram, explain how one connection differs from the other.
4. If 3 bulbs were connected, which connection would make the bulbs brighter and why?
5. What is the advantage of connecting resistors in parallel?
6. How does connecting resistors in parallel affect the potential difference?
7. Discuss the relationship between resistance and current in a parallel circuit.
ADDITIONAL RESOURCES:
ADDITIONAL RESOURCES:
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