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Science 9 Review Questions 8.2
1. What other forms of energy can electrical energy be converted into by a load?
Kinetic (motion), heat, light, chemical, sound
2. *What is an electric circuit?
It is a pathway that allows electrons to flow in a continuous ring
3. Explain how electrons in a circuit are like people on a waterslide.
Electrons are given energy (voltage) by the power source like people walk up the steps (get potential
energy).
Electrons in wires are like a person walking horizontally (not losing or gaining energy)
Electrons passing through the load (the device running on electricity) give some or all of their energy to the
load like a person sliding down a waterslide who transforms his potential energy into kinetic energy.
Electrons returning to the power source have zero energy like persons at the bottom of the slide and bottom
of the stairs have no potential energy.
4. *What are the four basic components of a circuit?
A source of electrical energy. Conducting wires to give a path for electrons to and from the energy source
and load. The load, a device that uses up the energy of the electrons, converting it to some other form. The
switch, a device to complete the circuit (turned on) or open the circuit (stopping the flow of electricity).
5. What is the purpose of a circuit diagram?
Circuit diagrams give an organized representation of the actual circuit. It is a quick, short-hand way to
show how a circuit works.
6. *From which terminal of a battery are electrons pushed?
Electrons are pushed from the negative terminal
7. When a battery is connected to a circuit, all the electrons throughout the circuit immediately start to
move. How is this possible considering that most of the electrons in the circuit are far from the
battery?
Science 9 Review Questions 8.2
Each electron is negative, all the same charge. If one is pushed by a negative voltage, it transmits a force
across a distance to the next electron which transmits its force over a distance to the next etc. Thus the
force exerted at one end is transmitted across a distance from one to the next causing almost instantaneous
movement throughout.
8. Why is the charge in a battery not an example of static electricity?
The charge in a battery is continuously made or built up through chemical reactions and can cause a steady
flow of electrons from one place to another.
9. *Define electric current.
Electric current is the amount of charges (coulombs of electrons) flowing past a point per second.
10. *What are the units of electric current?
Amperes or amps (A)
11. *What is the purpose of an ammeter?
An ammeter measures electrical current, the amount of electron flow.
12. *How is electron flow different from conventional current?
Electron flow is a flow of electrons from negative to positive. Conventional current is an imaginary flow of
positive charges from positive to negative.
13. What is the function of the battery in an electric circuit?
A battery provides the energy (voltage or “push/pressure”) to move electrons.
14. What are three different examples of loads?
A light, a motor, a heating element
15. *Draw and label each of the following circuit symbols:
a. Conducting wire
b. Cell
c. Battery
d. Light bulb
e. Open switch
Science 9 Review Questions 8.2
f. Closed switch
g. Voltmeter
h. Ammeter
16. *What is the amount of charge passing a given point every second called?
The amperes of electrical current
17. *State the correct units of electric current.
Amperes (A)
18. *What device is used to measure electric current?
Ammeter
19. *What is the difference between electron flow and conventional current?
Electron flow is a flow of electrons from negative to positive. Conventional current is an imaginary flow of
positive charges from positive to negative.
20. Explain the difference between static electricity and current electricity.
Static electricity is a charge build-up in a place that is not moving. Current electricity is electrons moving
through a conductor.
21. *A circuit contains a 3.0 V battery and a light bulb. Suppose the battery were replaced by a 6.0 V
battery. Would the electrical energy transformed in the light bulb increase or decrease? Use the
example of a waterslide to explain your answer.
The energy would increase, the bulb would glow brighter. This is like a water slide that is twice as high so
a person sliding down it would move faster and get more energy because of the extra height.
22. Explain how electrons are “pushed” through a conductor without having to touch other electrons.
Since electrons repel each other, if they get “pushed” to move at one end of a conductor, that push is
tranmitted throughout the entire conductor because it acts over a distance from one electron to the next to
the next throughout the conductor.
23. Explain how two conductors could have different current even though the electrons in each
conductor are travelling at the same speed.
Current is the number of electrons going by (how many) per second, not how fast the electrons are moving.
So in two conductors, the electrons will be moving at the same speed but in one there may be twice as
many moving which is twice the amps (amperes).
24. *Draw a circuit diagram for the circuit shown.
Science 9 Review Questions 8.2
25. *Draw a circuit diagram of the above circuit with an ammeter added.