Series and Parallel Circuits and Electromagnets

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Series and Parallel Circuits and Electromagnets

• Investigations 3 and 4 Review

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Series Circuits
A series circuit has only ONE pathway for current
to flow.
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Battery Orientation

• Multiple D-cells in a series must be placed
  negative to positive for the current to flow
  through the circuit.

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Examples of Parallel Circuits
Parallel circuits split into two or more pathways
before coming together at the D-cell.
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Series and Parallel - Compare!
Can you tell which circuit is a parallel and
which is a series? The one on the left is a
series circuit, as there is only ONE pathway for
the current.
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String of Lights

• In a series circuit, both components are
  connected in a row, with electricity passing
  first through one then the other.
• In a parallel circuit, electricity passes through
  both components at the same time.
• Which is better for a string of lights?

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Parallel!

• A major advantage of parallel circuits is that if
  one component malfunctions, the other continues
  to function. (See bottom right.)
• In a series circuit, when one component breaks,
  both components stop working ?. (See bottom left.)

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Electromagnets

• Using the electrical field produced from a
  battery, it is possible to create a temporary
  magnet.
• Because electric currents induce magnetic fields,
  wrapping a coil of wire around an object such as
  a nail or rivet and connecting it to a battery
  can create a magnet.
• The benefit of this type of magnet is that it can
  be turned on and off when it is needed.

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Real Life Electromagnet
This junkyard electromagnet can be turned on and
off.
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Components of an electromagnet

• Steel rivet (steel core)
• Wire
• D-cell (power source)
• Switch (to turn it on/off)

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Because electric current is running through the
wire, if you have more coils of wire on the steel
core, the electromagnet will be stronger. The
relationship between winds of wire around a core
and strength of force is
More winds of wire more strength
Fewer winds of wire less strength
This electromagnet has only a few winds of wire
and can only pick up only one metal shaving.
This electromagnet has many winds of wire and can
pick up many metal shavings.
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Time for a Quiz1. Series or ParallelWhich is
which?
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a) Parallel more than one pathway to the
D-cellb) Series only one pathway to the D-cell
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2. Which of these is NOT part of an
electromagnet

• Aluminum rivet
• D-cell
• Motor
• A and B
• A and C

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E

• An aluminum rivet would not be useful because
  aluminum cannot be induced as a magnet. (The
  core of an electromagnet must be STEEL.)
• A motor is not needed to create an electromagnet.
  The electromagnet runs because of the energy from
  the D-cell.

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• 3. What is the relationship between winds of wire
  around a core and strength of force of an
  electromagnet?
• Fewer winds of wire less strength
• More winds of wire more strength
• Both A and B
• Neither A nor B

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C (A and B are correct)

• More winds give the electromagnet more strength,
  but fewer winds reduces the strength!

This is a strong electromagnet. Look at all the
winds!
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Which D-cell orientation is correct?
A.
B.
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AD-cells must be oriented negative to positive.
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Which type of circuit is best for a string of
lights?

• A. Parallel
• B. Series

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A. Parallel

• In a parallel circuit, if one bulb goes out, the
  others will remain lit because each one has its
  own pathway to the power source. (That will make
  it much easier to find the broken bulb!)
• Good luck on your test!