Download Electricity and Magnetism Unit Test

Unit Test - Electricity and Magnetism
Sheela Ravindran and Joy Augustine
Knowledge and Understanding - 20 marks
Thinking and Inquiry - 20 marks
Application - 10 marks
Communication - 5 marks
Section #1:
Multiple Choice - Knowledge and Understanding (8marks)
1. All of the following are Fundamental Laws of Electric Charges, except:
a) Some neutral objects repel other neutral objects
b) Similar electric charges repel each other
c) Charged objects attract some neutral objects
d) Opposite electric charges attract each other
2. All of the following methods of charging objects are true, except
a) None of the following
b) Charging by contact leaves both objects similarly charged
c) Charging by induction and grounding leaves both objects oppositely charged
d) Charging by friction leaves both objects oppositely charged
3. Electric Current is measured in:
a) Amperes (A)
b) Elementary Charge (e)
c) Coulombs (C)
d) Volts (V)
4. The Law of Conservation of Charge states: electric charge is…
a) Neither created nor lost in an electric circuit, nor does it accumulate at any point in the circuit
b) Neither created nor lost in an electric circuit, but does accumulate at a given point in a circuit
c) Is created and lost equally in an electric circuit.
d) Is created and lost inversely in an electric circuit.
5. Kirchhoff's Voltage Law (KVL) states: around any complete path through an electric circuit…
a) The sum of the increases in electric potential is equal to the sum of the decreases in electric potential
b) The sum of the increases in electric potential is unequal to the sum of the decreases in electric potential
c) The sum of the increases in electric potential is inversely related to the sum of the decreases in electric potential
d) The sum of the increases in electrical potential is unrelated to the sum of the decreases in electric potential
6. Ohm's Law states: The potential difference between any two points in a conductor varies…
a) Directly as the current between the two points if the temperature remains constant
b) Directly as the current between the two points if the temperature increases
c) Directly as the current between the two points if the temperature decreases
d) Inversely as the current between the two points if the temperature increases
7. The Right-Hand Rule for a coil states: If a coil is grasped in the right hand with the curled fingers representing…
a) The direction of the electric current, the thumb points in the direction of the magnetic field inside the coil
b) The direction of the electric current, the thumb points in the direction of the magnetic field around the coil
c) The opposite direction of the electric current, the thumb points in the direction of the magnetic field inside the coil
d) The direction of the magnetic field, the thumb points in the direction of the electric current inside the coil
8. The Law of Electromagnetic Induction states: An electric current is induced in a…
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Unit Test - Electricity and Magnetism
Sheela Ravindran and Joy Augustine
a) Conductor whenever the magnetic field in the region of the conductor changes
b) Conductor whenever the magnetic field in the region of the conductor stays the same
c) Circuit whenever the electric current in the region of the circuit changes
d) Circuit whenever the electric current in the region of the circuit stays the same
Section #2: Matching: Knowledge and Understanding (12 Marks)
1. The Space around a charged object where forces of attraction
or repulsion act on other objects.
Electric Field
2. Results when charges flow in a particular direction
Direct Current
3. A device that measures the amount of electric current
in a circuit
Ammeter
4. The amount of work required per unit charge to move
a positive charge from one point to another in the
presence of an electric field
Electric Potential
Difference
5. A device that measures electric potential difference between
two points in a circuit
Voltmeter
6. Any device in a circuit that transforms electric potential energy
into some other form of energy, causing an electric potential drop
Load
7. Circuit in which charges have only one path to follow
Series
8. Circuit in which charges can move along more than one path
Parallel
9. An opposition to the flow of charge, resulting in a loss of
potential energy
Resistance
10. Whenever an electric current moves through a conductor, a
magnetic field is created in the region around the conductor
Principle of
Electromagnetism
11. A device that consists of a core of soft iron with two separate
coils of wire used to change the voltage
Transformer
12. The rate at which energy is used or supplied
Power
Section #3 - Short Answer: Thinking and Inquiry / Communication / Application
(20marks)
(5marks)
(10marks)
1. Explain the difference between Electron Flow and Conventional Current (or Electric Current). Explain why a scientist
would prefer one definition over the other. (T/I-1, A-1)
2. If a current of 10.0 A takes 3.0x102 s to boil a kettle of water requiring 3.6x105 J of energy, what is the potential difference
(V) across the kettle? (T/I-1)
3. Calculate the total electric potential difference across three 6.0 V batteries connected a) in series b) in parallel? (T/I-2)
4. Draw a mixed circuit with at least 4 different Electric Loads, 2 switches, 3 Sources of Electric Potential (2V each), and 1
Electric Meter. (T/I-1, C-2)
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Unit Test - Electricity and Magnetism
Sheela Ravindran and Joy Augustine
5. To construct a battery, cells can be connected in series or in parallel. If four 1.5 V cells are to be used to construct a
battery, how will the batteries compare if they are connected in series or all in parallel? Discuss in terms of the volts and
battery life. (T/I-1, A-1)
6. What current is drawn from a vacuum cleaner from a 115 V circuit having a resistance of 28 ? (T/I-2)
7. What power is dissipated by an electric frying pan that has a resistance of 12  and operates at a potential difference of
120 V? (T/I-2)
8. Draw a detailed diagram of the Right-Hand Rule for a conductor and explain. (T/I-1, C-2)
9. Explain the Motor Principle and provide a real life application for the principle. (T/I-1, A-1)
10. How does Faraday's Iron Ring work? What is a modern application of this technology? Explain. (T/I-1, A-2)
11. How does a Television Tube or Cathode Ray Tube work? Which laws and or principles does this technology rely on?
Explain (T/I-1, A-2)
12. Calculate the electric current, I3, in the circuit shown in Figure 1. (T/I-2)
I1= 2.5 A
I2=4.0 A
I0 = 12.5 A
I3= ?
13. Find the equivalent resistor when a 4.0  bulb and an 8.0  bulb are connected in parallel. (T/I-1)
14. Parts of an electric circuit may heat up and start to smoke. Describe how this could happen? What should you do if the
occurs a) in the classroom b) at home. (T/I-1, A-2)
15. A 12 V battery, an ammeter, a 5.0 A fuse (which will burn out if more than 5.0 A of current is in the circuit), and several
10.0  lamps are used in an experiment to find the effect of connecting resistances in parallel (Figure 2).
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Unit Test - Electricity and Magnetism
Sheela Ravindran and Joy Augustine
a) Determine the total resistance and current when the number of lamps connected in parallel is 1, 2, 3, 4, 5, and 6. (T/I-1)
b) What is the maximum number of lamps that can be connected before the fuse becomes overloaded? (T/I- 1)
c) Write and explain one conclusion for the experiment and how it applies to everyday life. (A-1)
Unit Test - Electricity and Magnetism
Marking Scheme and Solutions
Knowledge and Understanding - Matching and Multiple Choice - 20 marks
Thinking and Inquiry - Short Answers and Calculations - 20 marks
Application - Short Answer - 10 marks
Communication - Diagrams and Short Answer - 5 marks
Solutions
Multiple Choice - 'a' is the correct answer for all the questions (make sure you switch up the answers on a real test)
Matching- All the definitions are directly horizontal (beside) the correct matching word. (Again be sure to move the words around on
a real test)
Short Answer/Calculations:
1. Electron flow is a term used to indicate that the electric current in metals is due to the motion of electrons. This definition is used
by academics and scientists. It is based in the theory and principles of electricity. Whereas, conventional current describes electric
charges traveling through a conductor from the positive terminal to the negative terminal of the source of electric potential. This
definition is used in the application of electrical concepts by electricians, electrical engineers, etc. It is based on industrial standards
and practical uses.
2.
I = 10.0 A
Δt = 3.0 x102 s
ΔE = 3.6 x105 J
V=?
= 3.6 x105 J / (10.0A) (3.0 x102 s)
= 1.2 x 102 V
V = ΔE / I Δt
There is a potential difference of 1.2 x 10 2 V across the kettle
3. a) Series V0 = V1 + V2 + V3
V0 = 6.0 V + 6.0 V + 6.0 V
V0 = 18.0 V
Parallel V0
= 6.0 V
4. Any configuration for a complete circuit drawing is correct. Just make sure the students use the correct symbols and connections
as well as the right number of meters, sources, and loads.
5. Make sure the two drawings are correct. In series the batteries will produce more electric potential difference or volts however the
battery life will be short. Whereas, in parallel the volts will be smaller but the battery life will last longer.
6. V = 115 V
R = 28 ?
I=?
R = V/I I = R/V
= 28 / 115V
= 0.24 A
The current drawn is 0.24 A
7. R = 1.2 x101 
V = 1.2 x102 V
P=?
P = V2 / R
P = (1.2 x102 V) 2 / 1.2 x101 
P = 1.2 x 103 W
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Unit Test - Electricity and Magnetism
Sheela Ravindran and Joy Augustine
The power dissipated is 1.2 x 103 W or 1.2 kW.
8. Compare diagrams to Figure 3 on page 479 Physics 11 - Nelson
Conductor
Electric Current
Direction of Magnetic Field
Lines
Magnetic Field Lines
9. Motor Principle: A current-carrying conductor that cuts across external magnetic field lines experiences a force perpendicular to
both the magnetic field and the direction of electric current. The magnitude of this force depends on the magnitude of both the
external field and current, as well as the angle between the conductor and the magnetic field it cuts across. One application would
be the electric motor. See page 496-497 Nelson.
10. A primary circuit with a switch, coiled around a conductor, changes the magnetic field of the conductor causing a secondary
circuit to experience an induced electric current. AC generators use this discovery to work.
11. In a picture tube or cathode ray tube (CRT) electrons moving in a vacuum are deflected into phosphors by a magnetic field. The
colour of the light depends on the type of phosphors used. Read pages 516-517 Nelson. The technology relies on Faraday's
discovery (electromagnetic induction), Lenz's Law, Principle of electromagnetism, Law of magnetic poles, etc.
12. Applying Kirchhoff's Current Law:
I 0 = I1 + I2 + I 3
I 3 = I0 - I 1 - I 2
I3 = 12.5 A - 2.5 A - 4.0 A
I3 = 6.0 A
13. R1 = 8.0 
R2 = 4.0 
RP = ?
The electric current in I3 is 6.0A
1/ RP = 1/ R1 + 1/ R2
1/ RP = 1/ 8.0  + 1/ 4.0 
1/ RP = 3/ 8.0 
RP = 8.0  / 3
= 2.7 
The equivalent resistor is 2.7 
14. Circuits fail or short when cell terminals are not connected properly, fuses are tripped, electric current is larger than capacity,
electric potential difference (voltage) exceeds load capacity. Unplug or shut down the power sources immediately if it is safe to do
so, contact a teacher immediately, do not attempt to remove any wiring or touch any resistors! At home if the fuse has not tripped
make sure you try to shut down the power source, call an adult, or locate your household fire extinguisher. Call 911 if you are alone.
15. a) #1 Rp = 10 #2 Rp = 5  #3 Rp = 3.3 
I = 1.2 A
I = 2.4 A
I = 3.6
#4 Rp = 2.5  #5 Rp = 2  #6 Rp = 1.7 
I = 4.8A
I = 6.0A
I = 7.2 A
b) 4.
c) The more resistance in a circuit the harder it is for electrons to flow through the circuit. Overloading or tripping a circuit can occur
by attaching too many resistors or appliances like lamps.
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