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2. How can we make use of Ohm’s Law?
Circuit Basics

3. What is a circuit?
A continuous loop through which current flows from an area of high voltage to an area of low voltage.

5. Circuit Elements – Voltage Sources
battery

6. Circuit Elements – Resistances
fixed resistor
variable resistor
lamp

7. Circuit Elements – Switch

8. Circuit Elements – Measuring Devices
Measures: VOLTAGE
Connect to circuit: OUTSIDE
Measures CURRENT
Connect to circuit: INSIDE
voltmeter
ammeter

10. One Thing at a Time
Series Circuits

11. Definitions
series circuit – a circuit in which two or more elements are connected end-to-end so that a single loop of current is formed.

12. Series Circuit Rules
equivalent Resistance –> more resistors = more resistance
Req = R1 + R2 + …
current – same throughout circuit
I = I1 = I2 = …
voltage – voltages add up
V = V1 + V2 + …
All circuit components and the circuit as a whole must obey Ohm’s Law

13. V (V) I (A) R (Ω) R1 R2 R3 Total 2.5 0.5 5.0 4.0 0.5 8.0 1.0 0.5 2.0
5.0 Ω
8.0 Ω
2.0 Ω R1 R2 R3
7.5 V
V (V)
I (A)
R (Ω) R1 R2 R3
Total
2.5
0.5
5.0
4.0
0.5
8.0
1.0
0.5
2.0
7.5
0.5 15

14. V (V) I (A) R (Ω) R1 R2 R3 Total 75 1.5 50 180 1.5 120 225 1.5 150 480
50 Ω
120 Ω
150 Ω R1 R2 R3
1.5A
V (V)
I (A)
R (Ω) R1 R2 R3
Total 75
1.5 50
180
1.5
120
225
1.5
150
480
1.5
320