Download Unit 3: Gravitational, Electric and Magnetic Fields Unit Test

S. Grootveld
SPH4U
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Unit 3: Gravitational, Electric and Magnetic Fields
Unit Test
Name: ______________________________________
Knowledge & Understanding
15
Application
Thinking & Inquiry
18
Communication
5
6
Total
44
Part 1: Multiple Choice
_____ 1. Two charged spheres are 5.00 cm apart. One sphere has a charge of 2.50 x 10-4 C and the other
sphere has a charge of 3.20 x 10-5 C. The electric force between the two spheres is
a. 1.44 x 101 N
d. 2.88 x 10-4 N
-20
b. 4.44 x 10 N
e. 4.44 x 10-18 N
c. 2.25 x 1019 N
_____ 2.
a.
b.
c.
Magnetic field strength is measured in
N
N∙C
kg/C∙s
d. kg∙m2/s2
e. kg∙m/s2
_____ 3. Which of the following diagrams represents the field of force around a negative point charge?
a.
d.
b.
e.
c.
S. Grootveld
_____ 4.
a.
b.
c.
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The value of g on Saturn is 10.9 N/kg. The weight of a 2.5 kg mass on Saturn is
2.5 kg
d. 4.4 kg
4.4 N
e. 27 N
11 N
_____ 5. A positively charged rod is brought close to a neutral pith ball hanging by a thread. The pith ball
a. Becomes negatively charged
d. Is attracted to the rod and then
b. Is repelled by the rod and then
repelled by the rod
attracted to the rod
e. Remains hanging by a thread
c. Becomes positively charged
motionless and unaffected by the
rod.
_____ 6.
In the diagram below, a permanent magnet is pulled upward through a horizontal loop of wire.
Which of the following describes the induced current as viewed from above?
a. Clockwise then counterclockwise
d. Counter clockwise
e. No current is induced
b. Clockwise
c. Counterclockwise then clockwise
_____ 7. A conductor is located between the poles of a horseshoe magnet. Current flows in the direction
indicated by the arrow on the diagram.
In which direction will the conductor move?
a. Upward
b. Downward
c. Into the page
d. Left
e. Right
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SPH4U
Current Date
_____ 8. A proton of charge 1.6 x 10-19 C is moving east with a speed of 8.2 x 107 m/s, as it enters a
magnetic field of 2.5 T downward. The magnitude and direction of the magnetic force acting on the
proton is
a. 3.3 x 10-11 N [N]
d. 3.3 x 10-11 N [S]
b. 1.9 x 1011 N [S]
e. 1.9 x 1011 N [N]
c. 5.3 x 10-12 N [S]
_____ 9. Which of the following statements about the loop shown below is false? (the loop is horizontally
oriented).
a. The north pole of the loop is at the
bottom of the loop labelled Z.
b. The direction of the magnetic field
cannot be determined
c. The magnetic field goes up through
the loop
d. The magnetic field is strongest in the
inside of the loop
e. The south pole of the loop is labelled
X
_____ 10. Which of the following is NOT a similarity or difference between Coulomb’s Law and Newton’s
Law of Universal Gravitation?
a. The forces act along the line joining the centres of the masses or charges.
b. The electric force can attract or repel, depending on the charges involved, whereas the
gravitational force can only attract.
c. The universal constant G is very small and in many cases the gravitational force can be ignored.
Coulomb’s constant k is very large, so that even small charges can result in noticeable forces.
d. Coulomb’s law is the product of two masses, whereas Newton’s law of universal gravitation is
the product of two charges
e. The size of the force is the same as the force that would be measured if all the mass or charge
was concentrated at a point at the centre of the sphere.
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_____ 11. Which of the following diagrams most accurately depicts to field between two oppositely
charged plates?
a.
d.
b.
e.
c.
_____ 12. An object with a charge +q experiences an electric force FE when put in a particular location in
the electric field ξ. The positive charge +q is removed and an object with charge -4q is placed in the
same location in the electric field. This charge would feel an electric force of
a. -2FE
b.
c.
d.
−𝐹𝐸
2
−2𝐹𝐸
𝑞
−𝐹𝐸
4
e. -4FE
_____ 13. Given that in the diagram below, B is the magnetic field and v is the speed of the positive
particle, what is the direction of the magnetic force?
a. Right
b. Out of the page
c. Left
d. Into the page
e. Downward
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SPH4U
Current Date
_____ 14. If the point charge –q in the diagram below was absent, the electric field at point B would be E.
What is the electric field between the two point charges, -q and –q, at point B which lies at the midpoint
between the two charges?
a.
b.
c.
d.
e.
2E [right]
0
2E [left]
½ E [left]
½ E [right]
_____ 15. A sphere of charge +q is in a fixed position. A smaller sphere +q is placed near the larger sphere
and released from rest. Which one of the following best describes its motion?
a. Decreasing velocity and increasing acceleration
b. Decreasing velocity and constant acceleration
c. Increasing velocity and decreasing acceleration
d. Increasing velocity and increasing acceleration
e. Decreasing velocity and decreasing acceleration
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Short Answer
16. Explain the process of charging by induction using a positive rod, an electroscope, and a wire. Be sure to
mention the movement of charges and the final charge on the electroscope.
17. A charged particle moving along the + y-axis passes through a uniform magnetic field oriented in the =z
direction. A magnetic force acts on the particle in the –x direction. Does the particle have positive
charge or negative charge? How would the force change if the charge of the particle were to triple?
Explain.
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Problems
16. The International Space Station (ISS) orbits the Earth at an altitude of about 350 km above Earth’s
surface.
a. Determine the speed needed by the ISS to maintain its orbit.
b. Determine the orbital period of the ISS in minutes.
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SPH4U
Current Date
17. A ping-pong ball of mass 3.0 x10-4 kg is hanging from a light thread 1.0 m long, between two vertical
parallel plates 10 cm apart, as shown. When the potential difference across the plate is 420 V, the ball
comes to equilibrium 1.0cm to one side of its original position.
a. What is the electric field intensity between the plates?
b. What is the tension in the thread?
c. What is the magnitude of the electric force deflecting the ball?
d. What is the charge on the ball?
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SPH4U
Current Date
18. An electron starts from rest. A horizontally directed electric field accelerates the electron through a
potential difference of 37 V. The electron then leaves the electric field and moves into a magnetic field.
The magnetic field strength is 0.26 T, directed into the page, as shown below, and the mass of the
electron is 9.11 x 10-31 kg.
a. Determine the speed of the electron at the moment it enters the magnetic field.
b. Determine the magnitude and direction of the magnetic force on the electron.
c. Determine the radius of the electron’s circular path.