Physics Review

The following prescribed learning objectives will be tested on the provincial exam. Use the following as a guide to help you review for the exam. Be sure to use information in your Data Booklet to help you answer some of the questions

It is expected that students will:

10E1 state the relationships between charged objects

10E2 demonstrate how electricity results from the movement of charged particles such as electrons and ions

· current and static electricity

10E3 describe the interactions between magnetism and electricity and relate these to common devices

· common devices include motors, generators and solenoids

10E4 use apparatus to determine the relationships between current, voltage, and resistance in different types of circuits

· relating to Ohm’s Law

· correct placement of apparatus in a circuit

10E5 relate power and energy to common electrical devices

10E6 describe the distribution and safety considerations of electricity from its generated source to its use within the home

· including step-up and step-down transformers

· focus on distribution and safety considerations

10E7 apply knowledge and data to make recommendations for reducing energy waste

P1. A magnet is composed of small magnets known as: domains

P2. The ends of magnets are known as: magnetic poles

P3. An example of an insulator is: plastic, glass, and rubber

P4. An ammeter is connected in _____ into a circuit. series

P5. Atoms that lose electrons form: ions

P6. A plastic ball hanging by a string is attracted to a positively charged plastic rod. What can you conclude? It is either negative or neutral (because neutral objects are attracted to charged!)

P8. Which atomic particle carries the smallest amount of negative charge? electron

P9. Which atomic particle carries the smallest amount of positive charge? proton

P10. What is the neutral particle found in the core of the atom called? neutron

P12. A current of electricity will move best through: metals such as copper, aluminum, gold, silver

P14. When you measure electric current you measure: the amount of charge that passes a point in a wire in one second (simply analogy: the number of electrons passes a point in a wire per second)

P15. Current is measured in units called: amperes, amps, A

P16. Change 24.2 milliamperes to amperes. Divide by 1000, 0.0242 A

P17. The voltage of a battery tells you: energy

P18. The current drawn by a kettle is 12 A when it is plugged into a 120 V source. What is the resistance of the element in the kettle? 10 Ω

P19. The filament of a light bulb has a resistance of 240 Ohm. If it requires a current of 0.50 A to operate at full brightness, what voltage must be applied to this light bulb? 120 V

P20. What current is needed to operate a device with a resistance of 24 Ω if the source voltage is 120 V? 5.0 A

P21. Which device would you use to control the current in an electric motor? resistor

P22. To reduce energy loss in the form of heat, electric energy is transmitted over long distances at: high voltages

P23. The purpose of a transformer is to: change current and voltage to different level

P24. The voltage between the white ground wire and the red wire entering your house would be approximately: 120 V

P25. The frequency of household electricity is: 60 hertz

P26. Which unit is a measure of energy consumed? Watts (for power)

P27. Your electric meter reads 48987 kWh on March 1. Two months later it reads 49567 kWh. If electric energy costs $.05/kWh, what will your bill be for the two months? Used energy = 49567-48987=580kW•h, then multiply this by 5¢ per kW•h = $29.00

P28. Which elements are strongly magnetic? Iron, cobalt, nickel

P29. The first scientist who suggested that the earth behaved as if it had a magnetic field like a bar magnet was: Michael Faraday

P30. Who made the important discovery that a magnetic field exists around a conductor carrying a current? Hans Oersted

P31. Draw a diagram that correctly represents two cells in series driving electrons through two resistors in parallel with an ammeter measuring the total current from the cells and a voltmeter measuring the potential difference across the resistors.

P32. To measure the potential difference across a resistor the voltmeter should be connected in: parallel

P33. The flow of electrons is measured by an instrument called: ammeter

P34. A substance that does not allow electrons to flow is called: insulator

P35. A toaster draws 8 amps and runs on 110 V. How many watts does it use? 880 W

P36. What current would a 220 volt 1700 watt heater draw? 7.7 A

P37. Passing an electric current through a coil of wire wrapped around a piece of soft iron will:

√ a. form an electromagnet

b. cause iron to heat up

c. cause a short

d. all of the above

e. none of the above

P38. The force pushing electrons through an electric conductor is measured in units called: volts

P39. If six dry cells are connected in series, what will be the total voltage of the resulting battery if each cell is 1.5 volts? 6 x 1.5 = 9.0 V

P40. A battery that provides 4.0 amps in current is connected to a 2.0 Ohm resistor. What is the voltage of the battery? 8.0 V

P41. A battery supplying 12 volts is causing a current of 3 amps to pass through a resistor. What is the resistance of the resistor? 4.0 Ω

P42. The magnetic pole at the north end of our planet is really a: South Pole

P43. Standard cell have voltages of 1.5 V. What is the voltage of:

a) 3 cells in series? 4.5 V

b) 4 cells in parallel? 1.5 V

P44. Write the correct statement of Ohm's law? V = I R

P45. What is the frequency of household current in Canada? 60 hertz

P46. What is the maximum number of 100 W lights permissible on a standard household circuit? The standard is 15 A, so if max V = 120 V, total power would be P=IV=1800W. It would take 1800 W to trip the circuit breaker. Max number of 100 W bulbs would be 18.

P47. Which appliances need a 240 V circuit? Clothes dryer and stove (electric water heater)

P48. Which wire is connected to the casing of an appliance? ground

P49. What unit do power company's use when billing the householder for electricity: kilowatt-hour kW•h

P50. What power rating does an extension cord need to operate a string of forty 20 W Christmas lights? 800 W

P51. Draw the magnetic field interaction between two North Poles. Here is interaction between N and S as well as N to N

P52. Which of these does not use an electromagnet?

√a. tape recorder √b. telephone c. junkyard crane(possibly) d. cupboard door lock √e. transformer

P53. Where on Earth would a compass needle point towards the true geographic North?

Due south of Bathurst Island

Sample Test Questions: Circuitry

1. The instrument used to measure the current is called a(n)

√A ammeter B voltmeter C resistor D galvanometer

2. In which case will the light bulb(s) shine the brightest?

A two bulbs in series C three bulbs in series

B two bulbs in parallel √D three bulbs in parallel

3. When three dry cells (1.2 V) are connected in parallel, the voltage is

√A 1.2 V B 2.4 V C 3.6 V D 4.8 V

4. What kind of energy is present in a lemon cell?

A mechanical √B chemical C solar D gravitational

5. In order for a simple generator to work, it must have the following

A solenoid(coil of wire) C mechanical energy

B magnet √D all of the above

6. If you increase the resistance in a circuit, what happens to the current? ________________decreases

7. The energy transformation that takes place for a solar cell is _________light energy---> ___________electrical energy

8. What is the value and tolerance of a resistor that is labeled 0.15 M ________________ skip this!!

9. A material that allows electrons to pass through it is called a(n) ________________conductor

10. The rate of flow of electrons in a circuit is called the ___________current

11. Draw a circuit with two dry cells in series, one ammeter, one open switch, two light bulbs in series, which in turn are parallel to a resistor

12. What voltage is required to send a current of 10 A through a 22 ohm resistor? 220 V

13. Four 1.2 V batteries are connected in series to 120 ohm resistor. Find the current? V = 4.8 V, I = V/R = 4.8/120 = 0.040 A or 40 mA

14. Find the resistance if the voltage is 12.0 V and current is 600 mA. R = V/I = 12/0.6= 20 V

Sample Test Questions: Magnetism

1. Magnets that keep their magnetism for a long period of time are called ________________permanent magnets

2. The region in space around a magnet where its effects can be detected is called the _________________magnetic field

3. A coil of wire carrying a current is called a(n) ___________solenoid

4. Name another element besides iron that is easily magnetized ________cobalt or nickel or gadolinium

5. Approximately how far away is the geographic North Pole from the magnetic north pole _____________ 1500 km

6. Another name for a naturally occurring magnetic ore ________________magnetite

7. A group of magnetized atoms lined up in the same direction are called a(n) _______________magnetic domain

8. An isolated single magnetic pole is called a(n) _____________monopole

9. State two ways you could make a piece of iron magnetic.

a) align them with magnetic field from a permanent magnet

b) place them inside an electromagnet

10. State two ways you could destroy a magnet

a) heating it up

b) dropping it

11. State four devices that use magnets.(permanent or electromagnets)

a) TV c) dishwashers

b) stereo d) car

12. Explain why a horseshoe magnet is stronger than a bar magnet

the lines of magnetic field are closer together

13. State two ways that you could increase the strength of an electromagnet

a) greater current

b) more wraps (turns) of wires

Sample Test Questions: Household Circuitry

1. Name of the label that is required by law to be affixed to appliances so the consumer can compare the efficiency of similar appliances before purchasing __________________ Energuide

2. Energy is measured in ___________joules or _____________kW•h

3. A three-pronged electrical outlet is made up of a round slot, which is _________ ground, a short slot that is ______ hot and a long slot which is _____ neutral

4. A device that steps up or steps down voltage._____________ transformer (see pages124 to 131)

5. What is the power rating of an electric drill which draws 2.5 A at 120 V.

P = I V = 2.5 x 120 = 300 W

6. How much current does a 12000 W stove draw at 240 V?

P = I V and I = P/V = 12000 / 240 = 50 A

7. If it costs 5 cents /kw•h, How much will it cost to run a 150 W stereo for 10 hours?

E = P t and Energy = 0.150 kW • 10 h = 1.5 kW•h now multiply this value by 5¢ = 7.5¢

8. Will a 15 A fuse melt in a circuit with a voltage of 120V and a resistance of 8 ohms?

V = I R, I = V/R = 120/8 = 15 A. since fuse has now the maximum amount of current running through it, it will melt.

9. Explain how a circuit breaker works

see page 101 of your text. The current runs through breaker. Wires get hot as energy is lost to the wires (since wires are resistors!). If the bimetallic strip in the circuit breaker gets too hot it will bend, slip into the notch and trip the breaker. The compressed spring will expand and cause the contact points to separate.

Sample Test Questions: Static Electricity

1. What happens when a positively charged rod is brought near a neutral wooden ruler.

A protons on the ruler are attracted and move towards the rod

B protons on the ruler are repelled and move away from the rod

√C electrons on the ruler are attracted and move towards the rod

D electrons on the ruler are repelled and move away from the rod.

2. Black plastic rubbed with fur obtains a negative static charge. If it attracts a polyvinyl plastic strip, what is the charge on this strip?

A positive √C positive or neutral

B negative D negative or neutral

3. What subatomic particle moves when a static charge is transferred from one object to another? electrons

4. Where is most of the mass of the atom located? ____________nucleus

5. Materials that allow electrical charge to pass through them are called ____________conductors

6. An excess of nonmoving electric charge is called ____________static electricity

7. An atom with 6 electrons and 4 protons has what charge? __________-2

8. When glass is rubbed with silk it attains a positive charge. If this rod repels a vinyl strip, the vinyl strip has what charge?_________ positive

9. A device used to measure static charge _______________electroscope

10. Where are electrons found in the atom ___________outer part of atom

11. How would you describe a positively charge object in terms of electrons and protons. The material would have less that its usual number of electrons (as we know that electrons may be lost or gained) making more protons than electrons and giving the overall positive charge

12. State two ways that static electricity can be a nuisance or a danger and discuss these nuisances or hazards can be reduced. (2 marks)

Lightning kills people or damages the surroundings; conveyor belts in factories create hazardous electrostatic charge.

13. List four ways that static electricity can be used for the benefit of humans.

Photocopiers. Sandwich wrap, soaps, electrostatic spray painting, concentrators in metal refining

14. Why did the student (s) stand in a plastic tray and paper while touching the electrostatic generator to make their hair stand up?

Although we did not do this in our online class, here is an answer. The electrostatic generator pictured on the front of your Study Guide, makes a net negative charge. Anyone standing on an insulator (such as plastic) who touches this generator will have the electrons from the generator travel onto themselves. This causes hair to rise as each hair gains a negative charge and repels against other hairs.

15. What causes thunder and lightening?

Small dust particles, pushed by the wind, rub against each other, losing electrons, which in turn gives them a positive static charge. These charged particles collect in clouds, known as thunderheads. When the clouds get close enough to the ground, or to a cloud with a smaller positive charge, the charge is neutralized in a series of fast violent bursts of energy, known as lightening. In most cases, electrical charge flows up from the ground into the clouds. In the process, the air heats up and glows, producing the bright streaks, hence its name – lightning. The light from the flowing charge reaches us almost instantaneously, whereas the sound, known as thunder, travels at a much slower speed

16. Explain why can you make a stream of neutral water bend towards a positively charged plastic strip.

Charge a rubber rod or plastic comb positively and hold it near a thin stream of water coming out of the faucet (try this at home)