Transcript Electric Current

Electric Current
Electric Current
• Electric current- The flow of electrons through a
wire or any conductor.
• Measured in units of Amperes (A)
• Different from static electricity because it lasts longer
• Charges flow from High voltage to Low voltage
• Voltage difference- push that causes charges to
move- measured in volts (V)
• For charges to flow, the wire must always be
connected in a closed path, or circuit
Electrical Circuits
• Less resistance means less heat, which is
safer for use in your home
• Ohm’s law- current in a circuit equals the
voltage difference divided by the resistance.
• As resistance increases, current decreases
• As voltage difference increases, current
increases
Electrical Circuits
• Series circuit- current has only one loop to flow
through
• Parallel circuit- current has more than one loop
to flow through
• Magnetic fields form around wires through which
electricity is moving
• Electromagnet- a temporary magnet made by
placing a piece of iron inside a current-carrying
loop of wire
• More loops = stronger
• More voltage = stronger
• Only works for DC current
Resistance
• All materials have some electrical
resistance.
• Resistance is measured in Ohms
(Ω)
• Making wires thinner, longer, or
hotter increases the resistance
Electrical Circuits
• Circuits rely on generators at power
plants to produce a voltage difference
across the outlet, causing the charge to
Flow when the circuit is complete
• Series Circuit- the current has only
one path to flow through
Series Circuits
Series circuit
• The parts of a series circuit are wired
one after another, so the amount of
current is the same through every part
• Open Circuit- if any part of the circuit is
disconnected, no current flows
• Example- old style Christmas lights
•
Voltage Source
Wire- conductor
Load- like a bulb
Switch
Parallel Circuit
• Parallel Circuit- contains two or more paths for the
current to move through
Parallel Circuits
• Individual parts can be opened without affecting
the entire circuit
• Like the lights in your house
• Household circuits are parallel circuits
• Each branch receives 120 V from the electric
company
• Electrical energy enters your home at the circuit
breaker or fuse box and branches out to wall
sockets, major appliances, and lights
Circuits
• Guards against overheating electric wires:
• Fuses- contain a small piece of metal that
melts if the current becomes too high,
opening the circuit and stopping the flow of
current
• Circuit breakers- contain a small piece of
metal that bends when it gets hot, opening
the circuit and stopping the current