Bellwork (2/24)

What is a voltage source? A device, such as a dry cell, battery, outlet or

generator, that provides a voltage difference.

Electric Circuits II

True or False

1. When a battery no longer works, it is out of charge.

2. A battery can be a source of charge in a circuit. The charge which flows through the circuit originates in the battery.

3. Charge becomes used up as it flows through a circuit. The amount of charge which exits a light bulb is less than the amount which enters the light bulb.

True or False

4. Charge flows through circuits at very high speeds. This explains why the light bulb turns on immediately after the wall switch is flipped.

5. The local electrical utility company supplies millions and millions of electrons to our homes everyday.

6. High voltage circuit means there is a large current.

Voltage Sources

Do work on each charge it encountersWhich transfers into electric potential

energy

Circuit as a Waterslide

[ Illustration that was drawn on the whiteboard is on following slide ]

Waterslide vs. Circuit

Voltage Sources Examples

Ex 1) Low voltage and low currentD-Cell battery: 1.5 V and 0.1 ALow waterfall with only trickle of water

flowing

Voltage Sources Examples

Ex 2) High voltage and high currentPower lines: 50,000 volts

and 65 AHigh waterfall with a river

of water flowing over it

Voltage Sources Examples

Ex 3) High voltage and low current:Electric fence: 6000 V and 0.1 A High waterfall with only trickle of water

flowing

Voltage Sources Examples

Ex 4) Low voltage and high current:Car battery: 12 V and 30 ALow waterfall with a gushing river of

water flowing

All questions are FALSE!

1. When a battery no longer works, it is out of charge.

2. A battery can be a source of charge in a circuit. The charge which flows through the circuit originates in the battery.

3. Charge becomes used up as it flows through a circuit. The amount of charge which exits a light bulb is less than the amount which enters the light bulb.

All questions are FALSE!

4. Charge flows through circuits at very high speeds. This explains why the light bulb turns on immediately after the wall switch is flipped.

5. The local electrical utility company supplies millions and millions of electrons to our homes everyday.

6. High voltage circuit means there is a large current.

Homework

Electric Circuit IDue Thur. 2/27/14

Example

A 485 W LCD projector is plugged into a 120 Volt outlet and is used for 5 hours. The utility company charges you $0.14 per kW•hour. Calculate the cost of using the projector to the nearest cent.

Homework

Electric Circuit IDue Thur. 2/27/14