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Electric Circuits. Electric Circuits. When a wire is connected to the terminals of a source, a complete path called a CIRCUIT is formed An electric circuit provides a complete, closed path for an electric current. Parts of a Circuit. Voltage/energy Source Wires/conductors Closed circuit
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Electric Circuits • When a wire is connected to the terminals of a source, a complete path called a CIRCUIT is formed • An electric circuit provides a complete, closed path for an electric current
Parts of a Circuit • Voltage/energy Source • Wires/conductors • Closed circuit May also include: • Resistors • Switches
BATTERY/ VOLTAGE SOURCE SWITCH RESISTOR Circuit Diagrams (schematics)
Series Circuits • There is only one path for the electrons to take • If one part of the circuit opens, the whole circuit goes out.
RTotal= R1 + R2 + R3 + … • Current is the same everywhere in the circuit. I = V / RT • Voltage drop across each resistor device is current x resistance. V (drop) = I x R • Voltage thru battery is sum of voltage drops in circuit. VT = V1 + V2 + V3… Rules for solving series circuits
2 ohms 3 volts 6 V 3 ohms 4 ohms
Parallel Circuits • There are separate branches to the circuit • If there is a break in a parallel circuit, electrons can still move through the other branches
Separate conductive paths for each bulb /resistor connected to the voltage source • Any break in a branch, current stops in THAT branch ONLY. Current continues in the other branches. Parallel Circuits
1/RTotal = 1/R1 + 1/R2 + 1/R3 + … • Total Voltage = voltage across each branch • Vtotal = V1 = V2 = V3 … • I total = I1 + I2 + I3… (sum of I in all branches) Rules for solving Parallel circuits
3 volts 2 ohms 6 V 3 ohms 4 ohms 2 ohms 2 ohms 2 ohms
Pop goes the Fuse!! • Fuses protect against too much current flowing at once • Inside each fuse is a small strip of metal
FUSES • If the current becomes too high, the strip of metal melts and breaks the flow of electricity
When a fuse is blown, a small piece of metal melts if the current becomes too high. • This causes a break in the circuit, thus stopping the flow of current through the overloaded circuit. • Circuit breakers have a piece of metal that bends instead of melting and can be reset by changing it back to the on position. Fuses:
Series: • The current has only one loop to flow through. • Flashlights and some holiday lights • Amount of current is the same everywhere. • When any part of a series circuit is disconnected, no current flows through the circuit (open circuit). • Parallel: • Contain two or more branches for current to move through. • The current splits up to flow through the different branches. • Voltage difference is the same in each branch. • More current flows through the branches with lower resistance Electric Circuits: