Electric Current and Ohms Law

Electric Current The continuous flow of electric charge –The two types of current are direct current (DC) and alternating current (AC)

Voltage Potential difference: the difference in electrical –Measured in Volts (v)

In order for charge to flow in a conducting wire, the wire must be connected in a complete loop that includes a source of electrical energy

Ohm’s Law The Voltage in a circuit equals the product of the current (I) and resistance (R) –V=I x R or I = V R I- amperes R - ohms

Practice Problem What is the voltage if the resistance is 3 ohms and the current is 3 amps?

More Practice Problems What is the current if there is 10 volts, and 4 ohms of resistance? What is the resistance if there is 12 volts and 6 amps of current? What is the voltage if there is 4.5 amps and 6 ohms of resistance?

Increasing the voltage increases the current. Keeping the same voltage and increasing the resistance decreases the current.

Electric Circuit A complete path through which charge can flow.

Circuit diagrams se symbols to represent parts of a circuit, including a source of energy and devices that are run by electrical energy. –Switches can show if the circuit is open or closed

Series Circuits Charge has only one path through which it can flow

If one element stops functioning in a series circuit, none of the elements can operate. Example: christmas lights

Parallel Circuit An electrical circuit with two or more paths through which charges can flow

If one element stops functioning in a parallel circuit, the rest of the elements still can operate. Ex. Light bulbs in your house

Catalyst If I have a battery that can output 120 volts and a resistance of 30 ohms, what is the current that is able to flow through the circuit?

Electric Power The rate at which electrical energy is converted to another form of energy –Measured in Joule/second or Watt

P(watts) = I (amps) x V (volts)

Practice Problems An electric oven is connected to a 240-volt line, and it uses 34 amps of current. What is the power used by the oven?

More Practice Problems Every Time you use a watt hair dryer, you send through a current of 35 amps. What is the voltage used by the hair dryer? If you are using 250 volts and a power of 2500 watts, what is the current that runs through the circuit?

More practice problems 1-3 on page on page 613

Online practice online.com/objects/index_tj.asp?objID=dc e11904

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