Science 9 .ca
Science 9, Unit 4, Lesson 2 - Electrical Circuits
Text Reference
• Science Focus 9 pp. 272 to 278
Learner Outcomes
Students will:
Describe technologies for transfer and control of electrical energy
• use switches and resistors to control electrical flow, and predict the effects of these and other devices in given applications
• describe, using models, the nature of electrical current; and explain the relationship among current, resistance and voltage
• measure voltages and amperages in circuits, and calculate resistance using Ohm’s law
• develop, test and troubleshoot circuit designs for a variety of specific purposes, based on low voltage circuits
Background Information
Electric circuits provide a continuous pathway for charges to move.
1. Complete the following.
(a) Define electricity
(b) Complete the following system diagram.
|Input |Process |Output |
| | | |
| | | |
| | | |
| | | |
(c) Define an electrical circuit.
(d) Use the following diagram to identify and describe the key components in a circuit.
[pic]
Circuit Elements and Diagrams
Even the most complex electrical circuits are made up of only four basic elements or components.
• Source: the source of electrical energy (usually a battery)
• Conductor: the wire through which current flows
• Load: items along the circuit that convert electrical energy into other forms of energy
• Control: a switch or device that can turn the circuit or devices along it on or off.
Nearly everyone who designs and works with electrical circuits uses symbols and circuit diagrams. You have been provided with an illustration of the component. Complete the rest of the chart by (a) describing the component, and (b) drawing a sketch of the symbol used to represent the component. The last one has been done for you because it was not on this web page.
|Component |Description of the Component |Draw a Sketch of the Symbol Used to |
| | |Represent the Component. |
|[pic] | | |
| | | |
|[pic] | | |
|[pic] | | |
|[pic] | | |
| | | |
|[pic] | | |
|[pic] |To control electricity flowing in a |[pic] |
| |circuit it is sometimes necessary to | |
| |reduce the current. To do this we use | |
| |resistors and the amount of resistance is| |
| |shown on the resistor by a number of | |
| |coloured bands. | |
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