Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces...

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Chapter 34 Electric Current

Transcript of Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces...

Page 1: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Chapter 34

Electric Current

Page 2: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

The Big IdeaElectric current is related to the voltage

that produces it and the resistance that opposes it.

V = IRVoltage equals the current times the resistance

Ohm’s Law

Page 3: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Basic Facts

• We use the letter I to represent current.• Current is measured in Amperes.• Ampere or Amps or the Letter A.

• We use the letter R to represent resistance.• Resistance is measured in Ohms.• Ohms or the Greek letter omega .

Page 4: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Some Examples with

1. A Battery with 10Volts is hooked up in a circuit with a resistor at 100. Calculate the current that flows through the circuit.

2. You want 1 A to flow through a resistor of 1,000. What Voltage battery will you need?

3. You have a battery with 20V. You have 3 different resistors, 10 , 100 , 1000 . Which resistor will give the largest current? Which will give the smallest current?

V = IR

Page 5: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Power!

• To calculate the power used in a circuit is very similar to Ohm’s Law.

• Units for power are Watts (W).

V = IR

P = IV or P = I2R

Page 6: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Circuit

• A Complete Path

Page 7: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

We hook the battery up and make a circuit.

+

_

Page 8: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

How to Draw a Battery

Page 9: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Resistors

• Resists the flow of electrons.

• They get warm when they do this.

• Ex. A Light bulb.

Page 10: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Series and Parallel

• Series– More then one component in a row

• Parallel– One component, multiple paths.

Page 11: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Equivalent Resistance forSeries & Parallel

1

Rtotal=

1

R1

+1

R2€

Rtotal = R1 + R2Series

Parallel

Page 12: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Remember Charge.

• Battery has a positive (+) and a negative (-) side.

• The plus (+) side does not have enough electrons.

• The minus (-) side has too many electrons.• This difference is called a difference in

electric potential or more commonly a Voltage.

Page 13: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Why Electrons MoveElectric current is the flow of electrons.

Remember: Opposites attract. 1. Negative Charges want to move towards positive charges.

2. Electrons move freely through conductors.

3. If there are too many electrons in a place and they have a path to where there aren’t as many electrons, they will move towards that place.

Page 14: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

AC/DC• Direct Current (DC) Vs. Alternating

Current (AC)

Direct current stays the same while alternating current alternates with a given frequency.

Page 15: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Capacitors

• Another component of electric circuit is a capacitor.

• Commonly called a cap.

• They store charge and can be deadly!

• The units for caps are called Farad (F).

Page 16: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

A capacitor is just two conductors separated by an insulator.

Old Style Cap.Modern capacitors

Page 17: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.

Transistors

• Transistors are used in circuits in two ways.

• 1. As an amplifier. – Transistors can amplify signals.

• 2. As a switch. Transistors can act just like your light switch. – On, current flows,– Off, current does not flow.

Page 18: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.
Page 19: Chapter 34 Electric Current. The Big Idea Electric current is related to the voltage that produces it and the resistance that opposes it. Voltage equals.