Electric%20Circuits

1
Electric Circuits

• Series and Parallel Circuits

2
Light a bulb

• You are given
• Wires, a bulb and a battery.
• Your job is to
• Light the bulb.

3
To light a bulb, the most important thing is

• There must be a complete path, or NO GAPS. This
  is a CIRCUIT.

4
Electric Circuit

• An electric Circuit is any path along which
  electrons can flow.
• For a continuous flow of electrons, there must be
  no gap in the circuit.
• An electric switch must be closed for electricity
  to flow.
• There are two types of electric circuits
• Series Circuits
• Parallel Circuits

5
Series Circuits

• There is only a single path for electrons to
  flow.
• Disadvantage If one bulb fuses, the current in
  the circuit stops.

6
In a series circuit

• The current through each bulb is the same.
• The total resistance is the addition of all
  resistances.
• The current in the circuit is equal to the
  battery voltage divided by total resistance.

7
Series Circuit

• The total resistance in a series circuit is the
  SUM of all resistances.
• Ex The Total Resistance of two 8 O resistors
  connected in series is ____.
• What is the total resistance of three 4 O
  resistors in series?
• 444 12 O

8
Parallel Circuits

• Each bulb is connected to the battery terminals.
• Each bulb operates INDEPENDENT of each other.
• If one bulb fuses, it does not disrupt other
  bulbs.

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In a parallel circuit

• The voltage across each bulb is the same.
• The total current in the circuit equals the sum
  of currents in all the branches.

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Parallel Circuit

• The Total resistance for a pair of equal
  resistors in parallel is HALF the value of either
  resistor.
• Ex The Total Resistance of two 8 O resistors
  connected in parallel is ___.
• Ex The Total Resistance of two 10 O resistors
  connected in parallel is ___.

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Can I have three volunteers please?

• How can they arrange themselves to form a series
  circuit?
• How much current will flow through each?
• How much voltage will be across each?
• How can they arrange themselves to form a
  parallel circuit?
• How much current will flow through each?
• How much voltage will be across each?

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Differentiate between

• Series Circuit
• Only 1 path for current
• If one bulb fuses, current stops.
• Resistance of a series circuit is more
• Current in a series circuit is less
• Voltage is divided among all bulbs

• Parallel circuit
• Multiple paths for current
• If one bulb fuses, others still work
• Resistance of a parallel circuit is less
• Current in a parallel circuit is more.
• Voltage across all bulbs is the same

13
For now

• Open to Pg 714 and answer Q 2, 3, 5, 6, 7, 8, 9
• Next class, test on Electricity
• Next week Physics Finals