Science 9 Test Review
Unit 2 - Electricity
Scientist:____________________________
Learning Outcomes: Students can…
Static Electricity
• identify properties of static electrical charges:
– like charges repel
– unlike charges attract
– induced charges through polarization (or how charged objects can be attracted to neutral objects)
• explain the production of static electrical charges in some common materials (i.e. charging a sweater and a
balloon through rubbing; lightning; laser printers, Van de Graaff generator)
• define electricity, conservation of charge & static electricity
• define conductivity
• explain the difference between electrical conductors & insulators
• provide examples of electrical conductors & insulators
Current Electricity
• define electric potential or voltage (V)
• demonstrate how batteries work
• define electrical current (I)
• describe how electrical energy ‘flows’ through a closed circuit
• identify the unit of current, the ampere (A)
• explain the difference between alternating current (AC) and direct current (DC)
• define resistance and the ohm (Ω)
• define & apply Ohm’s Law (V = I*R)
• use an ammeter and a voltmeter to measure current and voltage in series and parallel circuits
• define & calculate electrical power (P), measured in watts (W)
• describe series and parallel (maximum two resistors) circuits involving varying resistance, voltage, and
current, using Ohm’s Law
• draw circuit diagrams, using current symbols for a cell, switch, battery, lamp, resistor, voltmeter & ammeter
• explain that precise language is required to properly interpret EnerGuide labels and to understand a utility bill
• give examples of the development of alternative sources of energy (such as wind generators and solar energy)
-------------------------------------------------------------------------------------------------------------------------------------Multiple Choice Questions: Answer the following questions by shading in the correct bubble.
1. Materials that are easily positively charged:
A. don't have neutrons
B. are made of atoms that gain electrons easily
C. are made of atoms that lose electrons easily
D. have more electrons than protons
2. What particles in an atom have an electric charge?
A. protons and nucleus
B. neutrons and protons
C. electrons and neutrons
D. protons and electrons
3. An object becomes electrically charged when:
A. electrons are created in it
B. electrons from it are destroyed
C. electrons are transferred to it
D. protons are created in it
4. Lightning does not involve:
A. Movement of charges within the cloud to separate them
B. Movement of electrons away from the cloud in the ground
C. Movement of protons from the clouds to the ground
D. Movement of electrons between clouds and the ground
5. How does friction cause static electricity?
A. Rubbing materials together displaces atoms, causing sparks to fly
B. Rubbing causes the protons to be stripped from the object
C. Rubbing materials together causes neutrons and electrons to exchange places
D. Rubbing materials together can strip electrons off atoms, causing one material to become
positively charged and the other to become negatively charged
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
6. You rub a balloon on your hair. The balloon becomes negatively charged; therefore, your
hair:
A. Lost electrons
B. Gained atoms
C. Gained neutrons
D. Lost protons
7. If you rubbed a glass rod with a silk pad, which of the following would be true: (Hint: use
the table in the Lesson #2 notes)
A. the glass rod would be positively charged; the silk pad would be negatively charged.
B. the glass rod would be negatively charged; the silk pad would be positively charged.
C. neither the glass rod nor the silk pad would be charged.
8. Conductivity is:
A. not dependent on free electrons
B. the ability of a material to transfer electrical energy
C. very similar in all materials
D. high in insulators
9. Materials that make good electrical conductors contain atoms with:
A. energetic electrons
B. more than 10 electrons
C. low conductivity
D. free electrons
10. An example of a good conductor is:
A. copper
B. glass
C. rubber
D. plastic
11. Materials that make good electrical insulators contain atoms with:
A. low conductivity
B. very few, if any, free electrons
C. energetic electrons
D. high conductivity
12. Electrical energy is conducted through a material by:
A. free electrons dissipating energy through friction
B. free electrons impacting and transferring energy to each other
C. an energetic electron passing all the way through the material
D. the conductivity of the atoms in the material
13. An example of a good insulator is:
A. copper
B. glass
C. steel
D. sea water
14. TRUE or FALSE: An object is neutral if it has equal numbers of positive and negative
charges.
15. TRUE or FALSE: Charging by induction requires two objects to touch.
16. TRUE or FALSE: The law of static electricity states that like charges attract.
17. Current is:
A. the flow of a conductor through charged particles
B. the random movement of electrons from atom to atom
C. only present when there is no voltage
D. the flow of charged particles through a conducting medium
18. The two types of current are:
A. indirect and alternating
B. directive and alternative
C. direct and alternating
D. direct and attenuating
19. Direct current:
A. is best for long-distance power transmission
B. is easier to transform to other voltages than alternating current
C. is the flow of electrons in one direction
D. causes the lights to flicker in your house
20. Alternating current:
A. is not used in houses because it is dangerous
B. cannot be created by generators
C. changes direction several times per second
D. is created by batteries
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
T
F
T
F
T
F
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
21.TRUE or FALSE: A circuit with more than one possible pathway is called a series
circuit.
22. TRUE or FALSE: A voltmeter is connected in parallel to a light bulb.
23. According to Ohm's law, increasing the voltage _____
A. increases current
B. increases resistance
C. decreases current
D. decreases resistance
24. Which of the following is a series arrangement of two batteries?
A.
B.
C.
F
T
F
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
A
B
C
A
B
C
D
A
B
C
D
A
B
C
D
A
B
C
D
D.
25. Which of the following is used to measure current?
A. ohmmeter
B. ammeter
C. electric meter
D. voltmeter
26. Which of the following shows resistors in parallel?
A.
B.
C.
T
D.
27. As more resistors are added to a circuit in series, the current in the overall circuit will
A. increase
B. decrease
C. stay the same.
28. As more resistors are added to a circuit in parallel, the current in the overall circuit will
A. increase
B. decrease
C. stay the same.
29. Power is defined as:
A. the rate at which energy is used per time.
B. the rate at which energy is used per distance.
C. the rate of electric charge (or coulombs) per second.
D. the amount of electric energy per electric charge (or coulomb).
30. On an Energuide label, the electrical energy consumption rate is expressed as:
A. kilowatt∙hours per meter.
B. kilowatt∙hours per year.
C. joules per meter.
D. joules per year.
31. Which of the following electrical production methods uses a non-renewable source?
A. Solar
B. Hydroelectric
C. Tidal
D. Coal
32. What is the proper sequence of steps in the process that uses hydroelectric power?
A. natural gas is burned → heat boils water to produce steam → steam turns turbines →
turbines run generators to produce electricity
B. uranium is split in a nuclear reactor to produce heat → heat boils water to produce steam
→ steam turns turbines → turbines run generators to produce electricity
C. sunlight falls on a solar panel → chemical reaction produces electricity
D. moving water from high to low places → water turns turbines → turbines run generators
to produce electricity
Short Answer Questions: Answer the following questions in the space provided.
33. Explain the following real-world situations or applications that involve static electricity. USE POINT
FORM in your responses. Also, refer to the diagrams provided in your response.
Lightning:
Van De Graaff Generator:
34. Refer to the PhET Balloons & Static Electricity lab. Explain how to produce an electrical charge on a
balloon using a sweater. Be sure to indicate what type of charge is produced on the balloon and sweater.
35. Refer to the PhET Balloons & Static Electricity lab. Once the balloon is charged and is brought near a
‘neutral’ wall without touching, how it is possible for the balloon to be electrically attracted to the wall?
Explain.
36. Is the type of charging described in #33 conduction or induction? ________________________
37. In the table below, list 5 good electrical conductors and 5 good electrical insulators:
Good Electrical Conductors
Good Electrical Insulators
38. CIRCLE the correct answer to the blank:
Batteries convert (chemical/electrical) energy to (chemical/electrical)
39. Using the proper schematic symbols, draw diagrams to illustrate the following scenarios. Put your diagram
in the space provided in the table.
Description of Scenario
a. Two bulbs connected in
parallel with a battery and a
switch.
Schematic Diagram
b. A battery connected to 3
bulbs connected in series and
with a voltmeter to measure the
voltage across one of the bulbs.
c. A battery connected to 3
bulbs connected in parallel and
an ammeter to measure the
current through one of the
bulbs.
For the following circuitry questions, remember that Ohm’s law can be represented as
For series circuits, the total resistance is:
and for parallel circuits, the total resistance is:
Power dissipated across a light bulb or resistor is:
P=I*V
40. Two light bulbs (40 Ω and 80 Ω) are connected in series and a voltage source of 24 V is used to light the
bulbs. An ammeter is connected to measure current through the circuit. A voltmeter is connected to measure the
voltage across the voltage source.
a. Draw the schematic diagram for this circuit.
b. What is the total resistance of the circuit? Show all work, including formula, calculations & correct
units.
c. What is the total current developed in the circuit? Show all work, including formula, calculations &
correct units.
41. Two light bulbs (50 Ω and 50 Ω) are connected in parallel and a voltage source of 24 V is used to light the
bulbs. An ammeter is connected to measure current through the circuit. A voltmeter is connected to measure the
voltage across the voltage source.
a. Draw the schematic diagram for this circuit.
b. What is the total resistance of the circuit? Show all work, including formula, calculations & correct
units.
c. What is the total current developed in the circuit? Show all work, including formula, calculations &
correct units.
d. What is the total power developed in the circuit? Show all work, including formula, calculations &
correct units.
42. A 4.0-Ω resistor is connected to a 12.0-volt battery with wires and a current is produced.
a. What is the current produced in the circuit? Show all work, including formula, calculations & correct
units.
b. What is the power dissipated in the resistor? Show all work, including formula, calculations & correct
units.
43. You are purchasing a refrigerator at Best Buy and notice its EnerGuide label:
a. What is the energy consumption rate of this refrigerator?
b. What is the least efficient among similar models of refrigerators?
c. What is the most efficient among similar models of refrigerators?
d. How would you rate the energy efficiency of this refrigerator, as compared to similar models? Why?
44. Electrical energy production in Halifax mostly involves coal. Explain a) how coal is used to produce
electrical energy & b) indicate whether coal is renewable or non-renewable source and why.
45. Explain an alternate electrical energy production method that uses Earth’s tides.
46. Describe 3 actions that conserve electrical energy in the home.