ELECTRIC CIRCUITS

1
ELECTRIC CIRCUITS

• By David Garcia P.5

2
Are all of the electrons flowing in a circuit
provided by the battery?

• I dont think so because the wires and the
  filament already consist of conduction electrons,
  the battery is just the power supply.

3
Why must there be no gaps in an electric circuit
for it to carry current?

• Current travels through free electrons (These are
  present in most transitional metals and some
  allotropes of carbon (I.E. Graphite)), when there
  is a break in a circuit (No metal present) the
  current cannot travel the gap, unless it is of
  sufficient energy to "arc" through the air to
  connect the gap. However this will only occur if
  completing the circuit is the easiest and
  quickest way to ground itself (Hence why people
  get electric shocks, we, being made up of mostly
  water, conduct electricity better than air, so
  the current passes though us to ground).

4
Distinguish between a series circuit and a
parallel circuit.

• In series circuits, the resistance adds up. In
  parallel circuits the resistance is reduced by
  the formula R1 X R2 / R1R2.

5
If one of 3 lamps blows out when connected in
series, what happens to the current in the other
two? What if it happened in a parallel circuit?

• If three lamps are connected in parallel and one
  blows out, the current in the other two does not
  change. This assumes that the net change in total
  current does not cause the power source to change
  voltage.

6
In which case will there be more current in each
of 3 lamps - if they are connected to the same
battery in series or in parallel?

• More current will be in case of parallel because
  in series combination resistance is greater with
  respect to parallel combination

7
What is meant by resistance in a circuit?

• Resistance of circuit is opposition offered to
  flow of current by that circuit.

8
What happens to the total circuit resistance when
more devices are added to a series circuit? to a
parallel circuit?

• The Circuit Resistance will increase.

9
What is the function of a fuse or circuit breaker
in a circuit?

• The main function is to quickly stop the power to
  continue threw the loop., and to protect
  ,equipment from damage and people from dying,
  that may be in contact to a shorted circuit.

10
Why will too many electric devices operating at
one time often blow a fuse or trip a circuit
breaker?

• Over current devices (fuse circuit breakers)
  primarily protect the conductors of a circuit
  from overheating damage.

11
What is meant by a "short circuit"?What is
meant by a "short circuit"?

• A circuit typically has a load on it, in a
  simplified model there is a power source, and a
  resistance in series with it. The power drawn
  from the source will be P I2 R. If the
  resistance was "short circuited", meaning a wire
  was run in parallel to the resistor from the
  positive side of the power source to the ground,
  the system would be short circuited. Maximum
  current would flow. In your house, short
  circuiting an outlet would be to take a piece of
  wire and plug one end into a power outlet, and
  the other into the other side of that same
  outlet. This will cause breakers (hopefully) to
  open in the breaker box in your house.