Unit 7: Electricity and MagnetismOhm’s Law and Introduction to Circuits

Resistance: As electrons move through a conducting wire, they collide with ________________ and _______ These collisions convert some ______________ energy into ______________ energy Because less energy is available to move electrons through the wire, the current is ______________. Resistance is ________________________ to the flow of charges in a material

o The SI Unit of resistance is the __________ milkshake analogy: resistance is lowered if you make a wire ________________ because more electrons flow

through it A material’s _________________________________________________________________ affect its resistance Resistance is _______________ in a longer wire because the charges travel farther As temp. increases, a metal’s resistance ____________________ because the e- collide more often

Charges can’t flow on their own without a source of __________________, or _____________________ In order for a charge to flow in a conducting wire, the wire must be connected in a complete ____________

that includes ________________________________________________________________________ Three common voltage sources are batteries, solar cells, and generators A battery is a device that converts chemical energy to _____________________ energy German scientist Georg Ohm determined how resistance & current affect ___________________,

the difference in _____________________________________________________ between any two points o It is known as Ohm’s law

o Formula: __________________________o The power equation: _______________

1. What resistance would produce a current of 200 amps with a potential difference of 1,000 volts? Given? 200 amps = current & 2,000 volts = voltage Looking for? Resistance (measured in ohms) Formula? V = I x R Answer: _______________________

2. What is the current produced with a 9-volt battery through a resistance of 100 ohms? Given? 9-volt = voltage & 100 ohms = resistance Looking for? ______________________________________ Formula? ______________________ Answer: _______________________

3. What is the current produced by a potential difference of 240 volts through a resistance of 0.2 ohms? Given? _____________________________________________ Looking for? ______________________________________ Formula? ______________________ Answer: _______________________

4. What resistance would produce a current of 120 amps from a 6-volt battery? Given? _____________________________________________ Looking for? ______________________________________ Formula? ______________________ Answer: _______________________

Back to Notes! An __________________ circuit is a complete path through which ______________ can flow An electrician uses _____________________________ to keep track of how different parts of a circuit are connected Circuit diagrams use __________________ to represent parts of a circuit, including a source of ____________________

_________________ and ______________ that are run by the electrical energy

Switches show places where the circuit can be ______________________ or _______________________ If the switch is open, the circuit is not a complete loop, & the current _________ - this is called an

_________________________________ When the switch is closed, the circuit is complete and charge ________ flow – this is called a

__________________________________o In a closed circuit, charge

_______________ flowo In an open circuit, charge

_______________ flow

In a series circuit, charge has only __________ path which it can flowo If one light bulb goes out, __________________________________

The bulbs in a circuit are a source of resistance Adding bulbs to a series circuit ________________________ the resistance

A parallel circuit is an electric circuit with _____________ or more paths through which charges can flowo If one light bulb on the strand goes out, the rest ___________________________

Series Parallel

Charge only has _______ path Charge has two or more paths it can flow

If one light bulb burns out, they all ___________ working

If one light bulb burns out, the rest ____________ working

Not used in your home Used in your home

#1 ________________ #2 _______________ #3 _______________ #4 _______________ #5 _______________

#6 ________________

Label the circuit diagram as either series or parallel

Label the following schematic circuit symbols

Fill in the table using

the PowerPoint