1. Electrical Circuits & Ohm’s Law
Circuit Diagrams
Series Circuits vs. Parallel Circuits
Ohm’s Law Calculations

2. 1) Circuit Diagrams
Circuit Diagram: a diagram that uses standard ______________ to represent the components in an electric _______________ and their connections.
In this case, the “resistance” is the ________________ in the _________.

3. 2) Series vs. Parallel Circuits
Series circuit: a circuit in which there is ____________________ path along which electrons can flow.
Series connections: specific places in a series circuit where components are connected. (One way)
Parallel circuit: a circuit in which there is ___________________ path along which electrons can flow.
Parallel connections: specific parts of a parallel circuit where there are more than one pathway. (Branched)
Most circuits in the real world are combinations of series and parallel circuits.

4. Check your understanding:
1) Label the following diagrams as series, parallel, or combination.
(Note: the longer line of a the cell represents the positive terminal).
( Hint: trace your finger from the (–) terminal to the (+) terminal).

5. Check your understanding:
1) Label the following diagrams with series or parallel.

6. Review of Electrical Characteristics

7. Review of Electrical Circuit Characteristics
Current (___)
Resistance (___)
Voltage (____)
________________________________
Definition
Unit of Measurement
How is it measured?
River Analogy

8. Check your understanding:
2) Draw a circuit diagram that shows a two-cell battery in series with a switch and two lamps in parallel. Include an ohmmeter correctly connected to one of the lamps.

9. Ohm’s Law
For most wires, the ratio of potential difference (V) to current (I) is a constant. The constant is called resistance (R)

10. Solving Problems - GRASP
G = Given – List known, draw diagrams
R = Required to find – Identify the unknown
A = Analyze – Write out formula
S = Solve – Plug knowns into formula
P = Present – State your answer using a sentence
You must GRASP a problem for full marks!

11. Sample Problem
Find the current through a 12 Ω resistor when 24 V are applied across it.

12. Check your understanding
A circuit consists of a 12 V battery connected across a single resistor. If the current in the circuit is 3 A, calculate the size of the resistor.

13. Sample Problem
2. An electric toy has a resistance of 120 Ω and requires a current of A to work properly. How many 1.5 V cells does the toy require?

14. Check your understanding
2. A circuit, in series, consists of a 225 V battery connected to 3 identical resistors. If the current in the circuit is 15 A, calculate the resistance of each resistor.