This document defines key electrical terms like voltage, current, and resistance. It explains that voltage is measured in volts and is the amount of energy per charge moving electrons. Current is measured in amperes and is the rate of charge flow. Resistance is measured in ohms and is the opposition to current flow. Ohm's Law is introduced, which gives the relationship between voltage, current, and resistance as V=IR. Examples are given to show how to use Ohm's Law to calculate current in different circuit scenarios. The document concludes by providing practice problems for readers to solidify their understanding of these concepts.

1. Bellwork: Write the meaning of each term (IN YOUR
OWN WORDS!) and write it’s unit:
Voltage
Current
Resistor

2. Voltage, Current and Resistance
 Voltage is the amount of energy per charge moving
electrons from one point to another in a circuit. It is
measured in volts (v)
Current is the rate of charge flow and it is measured in
amperes (A). Its unit is (I).
Resistance is the opposition of current
and it is measured in ohms (W)

3. What is Ohm’s Law?
Ohm’s law gives a relationship between the
voltage (V), current (I), and resistance (R)
as follows:

4.  Example #1
 A 4v battery is placed in a series circuit with
a 2W resistor.
 What is the total current that will flow
through the circuit?
I = ?
2W
4v

5. Solution
Given:
V = 4v
R = 2 W
I = ?
I = V/R
= 4v/2 W
I = 2A

6.  Example#2
A 110-V battery supplies a load with a
resistance of 3W,5W, and 7W
respectively, what is the current in the
circuit?
I = ?110v
3W
7W
5W

7. Solution
 Given:
 V= 110 v
 R1 = 3W
 R2 = 5W
 R3 = 7W
 I = ?
 Rtotal = R1 + R2 + R3 I = V/R
= 3 + 5 + 7 = 110/15
= 15 W = 7.33 A

8. How do we measure power in
electric circuits?
One watt is a pretty small amount of
power.
We often use kilowatts = 1000 watts

9. Formula of Power
 Power (watts)
P =
VI
Voltage (volts)
Current (amps)

10. Solution
 Given:
 V = 1.5v
 R = 3 W
 I =V / R P = V I
= 1.5 / 3 = 1.5 x 0.5
= 0.5 A = 0.75 watts

11. More Practice Problems
Page 841 #2-4
Page 853 # 3-4

12. More Practice
Read Pages 829-830
Do 1-4 on page 830

13. SC.912.P.10.15 - investigate and explain the relationships
among current, voltage, resistance, and power.
Unit Scale:
4 I can generate and test ways in which Ohm’s
law can help an electrician build more
energy efficient homes.
3 I can explain the relationships among
current, voltage, resistance, and power.
2 I can compare the differences between
current and voltage.
1 I can define these words using a dictionary
Agenda: Circuit Stations