Download Electric Circuits Prentice Hall

Electric Circuits
Prentice Hall: Electricity and Magnetism
Chapter 2, Section 4
Mrs. Brunner
Science
Visit www.phschool.com for review
I. Ohm’s Law
A. George Ohm (1800) – discovered relationship between current,
voltage, and resistance
B. Ohm’s Results
1. Changing the voltage in a circuit changes the current, but
will not change the resistance
C. Calculating Ohm’s Law
1. puts the relationship between current, voltage, and resistance
into numbers
2. resistance is equal to the voltage divided by the current
resistance = voltage
current
3. another way to write the equation is
voltage = current x resistance
D. Practice with problems in the book!
II. Features of a Circuit
A. Devices that run by electric energy
B. Has a source of electrical energy
C. Circuits are connected by wires
III. Series Circuits

A. type of circuit that has only path for the electricity to travel on

B. if one device on the circuit goes out, all the devices go out – this
is a problem

C. the more light bulbs you add to a series circuit, the dimmer they
become…Why?
•
1. bulb acts as a resistor
•
2. when resistance increases, current decreases

IV. Parallel Circuits

1. type of circuit where there are several paths for the electricity to travel on

2. If one device goes out, other devices on the circuit do NOT go out

3. When you add a ‘branch’ to a circuit, the overall resistance decreased

4. If resistance decreases than the current will increase so any light bulbs on
the circuit will not get dimmer

V. Ammeter – device that measures current

VI. Voltmeter – device that measures voltage or potential energy
difference, most circuits in your house can carry 120 volts