Big Question: How is
current
electricity different from
static electricity?
Not all electricity is the same. The charges in static electricity do not move. On the other hand, current electricity is used when charges move and we use them to power things like lights or our smart phones.
At the end of this inquiry, you should be able to answer the following questions:
What is the difference between current electricity and static electricity?
What are the components of a circuit?
What do an
ammeter
and a voltmeter measure?
What is meant by the term potential difference?
Pages 279 to 283 in your textbook will help you answer these questions about current electricity.
Introduction
Current Electricity and Circuits
What do the items in figure 1 have in common? They all use electricity to run. Imagine if electricity was in the form of static electricity where electrons jumped and discharged constantly. Devices requiring electricity as you know
it would be very painful to use if they worked at all.
Figure 1 – Some common household electrical items.
Fortunately, we have the technology to make electrons flow on a continuous bases. We call electricity that flows continuously current electricity
.
To have current electricity, we need a path in which the electrons travel. This path is the circuit. A circuit is made of four components:
Source
– where the electrical energy comes from, such as battery, outlet, generator
Conductor
– wire or material that allows the electrons to flow through (pathway)
Control
– switch that opens or closes the circuit (turns devices on or off)
Load
– the item or device that converts the electrical energy into ‘work’, such as light bulbs, speakers, motors, ovens
Circuits can be either open or closed. An
open circuit occurs when the switch is turned off. A
closed circuit occurs when the switch is turned on.
Figure 2 – A simple electrical circuit consists of a source, a load, a conductor, and a switch.
Match the letter with the appropriate component of a
basic
circuit in Figure 2.
Figure 3 – An ammeter measures the current in a electric circuit.
Current and Voltage
The rate at which electrical current flows is measured by amperes, often called ‘amps’. Amperes measure the charge per second that moves through a point on a wire. The symbol for representing current is I and the unit is Amps.
Two instruments can measure current:
a) A galvanometer is used to measure weak current such as in a watch.
b) An ammeter is used to measure a stronger current such as a hair dryer uses.
Another important part of learning about electric circuits is understanding voltage. This energy is available in the circuit to help power the load. Voltage is measured in units called volts represented by the symbol V.
Voltage is unique in that it has another name - potential difference. We measure voltage with an instrument called a voltmeter.
Electric Circuits Around the World
If you have ever travelled to another country and taken an electrical device with you, you will see that you cannot always use that device in that country. Two things can prevent you from doing that.
First, countries might have their own plug designs. Some have two prongs, some have three prongs, and the sizes of prongs vary.
As well, the voltage (potential difference) coming from the electrical sockets is different in Canada and United States than in many other countries. For example, a hair dryer purchased in Canada for 120 V socket would not be able to handle the
220 Volts that come from a European electrical socket. If you tried to plug it in, you could cause the hair dryer to start on fire.
Complete the worksheet while you watch the video "Current and Voltage" below. Refer to pages 279 to 281 in Science in Action if you need further help.
When you are satisfied with your responses you can check your work by clicking on the "SUGGESTED ANSWERS" button below.
Wait! Don't
view the suggested answers first. This practice work is not for marks,
it is meant to help you check your understanding. Check the answers
AFTER doing the questions! Keep the practice worksheet for study
purposes. If you don't understand something, contact your teacher!
