Download Electricity and Magnetism TEST

Electricity and Magnetism TEST – Honors Physics
Name: ________________________________
Multiple Choice: Choose the best answer (2pts each)
____ 1. An attracting force occurs between two charged objects when the charges are of
a. unlike signs.
c. equal magnitude.
b. like signs.
d. unequal magnitude.
____ 2. When a glass rod is rubbed with silk and becomes positively charged,
a. electrons are removed from the rod.
c. protons are added to the silk.
b. protons are removed from the silk.
d. the silk remains neutral.
____ 3.The figure shown to the right demonstrates charging by
a. grounding.
c. polarization.
b. induction.
d. contact.
____ 4. Two point charges, initially 1 cm apart, are moved to a distance of 3 cm apart. By what factor do the resulting
electric and gravitational forces between them change?
a. 9
c.
b. 3
d.
_____5. A wire carries a steady current of 0.1 A over a period of 20 s. What total charge moves through the wire in this
time interval?
a. 200 C
c. 2 C
b. 20 C
d. 0.005 C
_____ 6. A flashlight bulb with a potential difference of 4.5 V across it has a resistance of 8.0 Ohms. How much current is
in the bulb filament?
a. 36 A
c. 1.8 A
b. 9.4 A
d. 0.56 A
____7. What happens when the switch is closed in the circuit shown to the right?
a. The lamp lights because current from the battery flows through the lamp.
b. Current from the battery flows through the resistor.
c. Current from the battery flows through both the lamp and the resistor.
d. The lamp goes out, because the battery terminals connect to each other.
____ 8. If a 9.0 V battery is connected to a lightbulb, what is the potential
difference across the bulb?
a. 3.0 V
c. 9.0 V
b. 4.5 V
d. 18 V
____
a. a
b. b
9. Which compass needle orientation in the figure above might correctly describe the magnet’s field at that point?
c. c
d. d
_____ 10. A current in a long, straight wire produces a magnetic field. These magnetic field lines
a.
radiate out from the wire to infinity.
b.
come in from infinity to the wire.
c.
form circles that pass through the wire.
d.
form circles that go around the wire.
____ 11. An electric current that changes directions at regular intervals is called
a. directional current.
c. reversible current.
b. alternating current.
d. fluctuating current.
____ 12. According to the right-hand rule, if a current-carrying wire is grasped in the right hand with the thumb in the
direction of the current, the four fingers will curl in the direction of
a.
c.
the magnetic force,
.
the current’s velocity, .
b.
_____ 13.
a.
b.
c.
d.
d.
the magnetic field, .
the current’s path, .
Under which of the following conditions is the net magnetic force on a charged particle equal to zero?
when the particle is stationary
when the particle is moving parallel to the magnetic field
when the particle is not charged
all of the above
_____ 14. An electron moves north at a velocity of 4.5 x 10 m/s and has a magnetic force of 7.2 x 10
it. If the magnetic field points upward, what is the magnitude of the magnetic field?
a. 1.0 mT
c. 3.6 mT
b. 2.0 mT
d. 4.8 mT
____ 15.The direction of the force on a current-carrying wire in an external magnetic field is
a. perpendicular to the current only.
b. perpendicular to the magnetic field only.
c. perpendicular to both the current and the magnetic field.
d. parallel to the current and to the magnetic field.
_____ 16. All of the following are ways to induce an emf in a loop of wire except which one?
a. Move the loop into or out of a magnetic field.
b. Rotate the loop in a magnetic field.
c. Move the loop parallel to a magnetic field.
d. Insert the loop into a changing magnetic field.
_____ 17.
According to Lenz’s law, the magnetic field of an induced current in a conductor will
a. enhance the applied field.
b. heat the conductor.
c. increase the potential difference.
d. oppose a change in the applied magnetic field.
Short answer
18.
Materials, such as glass, in which electric charges do not move freely are called
electrical ____________________. (1pt)
19.
Is the charge shown in the figure to the right positive or negative? _________________(1pt)
20. In the circuit shown to the right, what will happen when the switch is closed? Explain.
(2pts)
N exerted on
21.
Draw the lines of force representing the electric field around two charges if both charges are positive and of the same
magnitude. (2pts)
22. Ola says that the lightbulbs in the circuit below light up at exactly the same time when
the switch is closed. Marco says that even though we can’t see it, that lightbulb A
lights up first, then B because the electrons start in the battery and take some time
to make it around. Who is correct? Support your answer. (2pts)
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23. What is a turbine’s rotational motion used for in commercial power plants? (1 pt)
24. Find the direction of the force on a proton moving
2
through the magnetic field shown to the below. (2pts)
25. Find the direction of the force on an electron moving
through the magnetic field shown above. (2pts)
26. If all circuits are connected to the same strength battery with the same resistance bulbs, discuss the current in
each of the wires A,B,C,D and E. (3pts)
*27. When asked, go to the desk with Ms. Brock and build the challenge. You will have 4 minutes to complete the
challenge then draw the corresponding schematic diagram (4pts) _______________
Problems Solving:
28. A constant electric field directed along the positive x-axis has a strength of 2.0 x 103 N/C. (4pts)
a. Find the electric force exerted on a proton by the field
b. If it starts from rest, how far does it travel in 3.4 x 10-6 seconds.
29.
Two equal charges are separated by 3.7 x 10
What is the magnitude of q on the charges? (k = 8.99 x 10 N•m /C ) (3pts)
30.
Charge A and charge B are 5.0 m apart. Charge A is -1.0 C, and charge B is -9.0 C. Charge C, which is +4.0 C, is
located between them and is in electrostatic equilibrium. How far from charge A is charge C? (3pts)
31. A wire 48 m long carries a current of 18 A from west to east. If a magnetic field of
south is acting on the wire, find the direction and magnitude of the magnetic force. (3pts)
32. A bar magnet is positioned near a coil or wire, as shown to the right.
What is the direction of the current in the resistor (left to right or
right to left) when the magnet is moved to the left, as in (a)? To the
right, as in (b) (2pts
a. _______________
b. _______________
N.
directed toward the