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# Electricity - PowerPoint PPT Presentation

Electricity . Part 2: Electric Current. Electric current is the amount of charge moving past a point. Maxwell Demon counting the charges passing a given point. Definition of current. I = current Q = amount of charge that passes point. t = time for charge to pass by. Units of Current.

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## PowerPoint Slideshow about 'Electricity' - jagger

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Presentation Transcript

### Electricity

Part 2: Electric Current

Maxwell Demon counting the charges passing a given point

• I = current

• Q = amount of charge that passes point.

• t = time for charge to pass by.

1 Ampere (Amp) = 1 Coulomb/second

• True

• False

Solar wind interacting with the earths magnetic field

2) Aurora from space

3) Aurora from ground

CME animation

Aurora from space

Aurora effects

Tokamak Fusion ExperimentsJET discharge

We usually think of currents in wiresOpening switch

• When a charged particle passes through the battery, it gains energy.

• When the particle passes through the light bulb it gives up the energy as heat.

Ohm’s LawV=IR

• V= Voltage of the Battery.

• I=current in circuit.

• R=Resistance in the bulb/resistor. (Depends on materials and geometry.)

• R=V/I (volts/amps)

• By definition, 1Ohm = 1 volt/amp,

or

1=1V/A.

• How many amps of current would flow in a light bulb that has a resistance of 60 if it is connected to a 12 V battery.

• When Charge Q passes through the battery it gains an amount of energy

E=(Q)V

(This is the amount of work the battery does on the charge.)

Which type of light bulb has a larger resistance, a 100W bulb or a 60W bulb?

• The 100 W bulb

• The 60 W bulb

• They will have the same resistance

• None of the above

Example Calculation bulb or a 60W bulb?

What is the resistance and how much current flows through a 100 W bulb?

Note: The wattage on a bulb is its power output and assumes that you will use it in the US where the voltage in 110 V.