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objectives
objectives
Series and Parallel
Series and Parallel
- The lamps above have to get their power from the same supply.
- There are two basic methods of connecting lamps, resistors, or other components together.
- The circuits below demonstrate the differences between them.
These lamps are connected in series.
- The lamps share the p.d. (voltage) from the battery, so each glows dimly.
- If one lamp is removed, the other goes out because the circuit is broken.
These lamps are connected in parallel.
- Each gets the full p.d. from the battery because each is connected directly to it. So each glows brightly.
- If one lamp is removed, the other keeps working because it is still part of an unbroken circuit.
Circuits and Switches
Circuits and Switches
- If two or more lamps have to be powered by one battery, as in a car lighting system, they are normally connected in parallel.
- Each lamp gets the full battery p.d. Also, each can be switched on and off independently:
- These diagrams show two different ways of drawing the same circuit for independently switched lamps.
Basic Circuit Rules
Basic Circuit Rules
- There are some basic rules for all series and parallel circuits.
- They are illustrated by the examples below.
- The particular current values depend on the resistances and p.d.s.
- However, the equation on the right always applies to every resistor.
When resistors or other components are in series:
- the current in each of the components is the same
- the total p.d. (voltage) across all the components is the sum of the p.d.s across each of them.
When resistors or other components are in parallel:
- the p.d. (voltage) across each of the component is the same
- the total current in the main circuit is the sum of the currents in the branches.
Cell Arrangement
Cell Arrangement
- These cells are connected in series.
- The Total p.d. (voltage) across them is the sum of the individual p.d.s.
- Here, a mistake has occurred. One of the cells is the wrong way round, so it cancels out one of the others.
- The p.d. across parallel cells is only the same as from one cell.
- But together, the cells can deliver a higher current.
Series and parallel circuits I worksheet
Series and parallel circuits I worksheet
8.09---Series-and-Parallel-Circuits.docxPage updated
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