PhysicsElectricity

Review

• Circuits are fairly simple to solve, but only involve MOVING charges.

• Remember the point charges we did the other day?

• If two charges q1 and q2 are 1 meter apart, and have a charge of 1 Coulomb each, with what force will q1 push on q2?

Review…cont.

•

• q1= 1C

• q2= 1C

• r= 1m

• K= 8.99*10^9

•

• =

• = 8.99*10^9 N of force. That’s the equivalent of 1 billion pokes at the same time. These forces are huge! (That’s why we use tiny point charges most of the time).

Key Terms(Watch for these during the lesson.)

• Voltage

• Current-Units are called amps

• Ohm’s law

• Power

Lesson Objective

• Students will be able to use Ohm’s law to determine current and voltage in a system and interpret Ohm’s law to find missing parts of a circuit.

You will be successful if…

• If you can answer the questions on peardeck at the end of the lesson.

Introduction

• Circuits carry charges from one place to another.

• If you picture a battery, there’s a positive end and a negative end. When you attach them with a wire, current flows from the negative side to the other (positive).

• There is nothing to stop this flow or slow it down, so as much electricity as possible rushes through from positive side to negative side.

• This is where a Resistor comes in. It resist the flow, much like a dam.

Imagination time!(cuz electricity is hard to see in action)

• Current can be imagined as how much water flows through a river (in our case how much electricity flows through the wire).

• Voltage can be thought of as “how much pressure there is in the current.”

• Resistors slow the current down and reduce the pressure (read current slows down).

Try answering: What is the resistor in this circuit?

What supplies the current?

This is how we draw a circuit

A circuit has 3 parts, Voltage (V)Current (I)Resistance (R)

Scientist noticed the amount of current flowing in a circuit depended on how much resistance the circuit had. The only way to overcome this resistance was with more voltage (pressure).

Heavy

• Ohms Law-

• This law allows us to find how much current is flowing through a wire at any given point.

Heavy

• Lets solve one-

• If we have a circuit, and it has 12 volts, for power, and a resistor, what is the current flowing through the circuit?

• If we doubled the voltage, what might happen to the resistor?

• What about the current?

Example

Try solving one on your own.

• Ok, this time lets use the Electric Eels voltage 600 volts.

• If your human body’s resistance is 1000.0, how much current went through your body?

Helpful hints:

• Using Ohms law V=IR Plug in your known values.

• Given: • V

• R

To find I adjust Ohms law to

Solve:

• Why would getting shocked by an electric eel hurt a lot?

Examine the following data

• Human body R=1000

• Electric Eel V= 600 volts

• A= .6 ampere (maximum value)

• If an electric eel was capable of putting out 1200 volts, what effect would this have on the current in the system? Why? (write a paragraph and explain, support your answer)

• What do can determine about the relation between resistance and current based on the above statement.

Check for understanding

Peardeck

Link to Haiku

Classwork