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 encounters  Which 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 current  D-Cell battery: 1.5 V and 0.1 A  Low waterfall with only trickle of water flowing

Voltage Sources Examples  Ex 2) High voltage and high current  Power lines: 50,000 volts and 65 A  High 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 A  Low 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 I  Due 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 kWhour. Calculate the cost of using the projector to the nearest cent.

Homework  Electric Circuit I  Due Thur. 2/27/14