Download exam - Charlestown SQR

Name _____________________
Period ________
Date ________________
Electricity and Magnetism TEST *
Part 1: Vocabulary: Fill in each blank with the matching vocabulary term. Each term can be used more than
once.
Resistance
Voltage
Current
Power
1. ______________________ How fast electrons are moving in a circuit
2. ______________________ This can be seen by the brightness in a lightbulb or the loudness of a
speaker
3. ______________________ This is measured in wires by an ammeter
4. ______________________ This is how much energy each electron carries.
5.
______________________ This comes from the battery and pushes the electrons through the circuit
6. ______________________ How much a wire or circuit element pushes back on electrons and slows
them down
Part 2: Equations: Fill in each triangle with the appropriate equation and write the other forms of the equation.
P=IV
V=IR
I=
I=
V=
R=
Part 3: Circuits: Match each element of the circuit diagram
Lightbulb
_____________
Wire
_____________
Resistor
_____________
Switch
_____________
Battery
_____________
Part 4: Multiple Choice
1. Based on Ohm’s law, which of the following statements explains what must happen when the
voltage across a resistor is decreased?
How do you know?
A. The resistance of the resistor increases.
B. The resistance of the resistor decreases.
C. The current through the resistor increases.
D. The current through the resistor decreases.
2. A copper sphere, a glass sphere, a plastic sphere, and a rubber sphere are placed on individual
insulating stands. A student touches each sphere with an electrically charged object. The sphere
made of which material will distribute the electric charge fastest over its entire surface area?
A. copper
B.
glass
C.
plastic
How do you know?
D. rubber
3. Why does a plastic rod have a negative charge after being rubbed with a piece of fur?
A. The fur gives up protons to the rod.
How do you know?
B. The rod gives up electrons to the air.
C. The fur gains protons from the rod.
D. The rod gains electrons from the fur.
4. A magnetic compass is placed near an insulated copper wire. When the wire is connected to a
battery, the compass needle changes position.
Which of the following is the best explanation for the movement of the needle?
A. The copper wire magnetizes the needle to create a force.
B. The needle magnetizes the copper wire to create a force.
C. The current in the wire produces a magnetic field and exerts a force on the needle.
D. The insulation on the wire becomes energized and exerts a force on the needle.
How do you know?
5. An engineer connects a 4W light bulb in a circuit. If the engineer wants to keep the bulb at the
same brightness while adding another light bulb in series, which of the following must be true
about this new circuit?
How do you know?
A. The new circuit will have twice the current
B. The new circuit will have half the resistance
C. The new circuit will require twice the battery voltage
D. The new circuit will require 4 times the power
6. Three positive point charges are lined up in a straight line along the x-axis, with a negative point
charge at the origin. Between which pair of charges will the force of attraction be the greatest?
X
+2
A.
B.
C.
D.
-1
Between charge Y and the negative charge
Between charge X and the negative charge
Between charge Z and the negative charge
Not enough information to know
Y
Z
+2
+1
How do you know?
7. A student builds a circuit with a 12V battery connected to a 6 resistor. What is the power in
this circuit?
Show your work:
Then find the Power.
A. 24 W
C. 6 W
B. 12 W
D. 2 W
First find the current.
8. The circuit diagram below shows three resistors,
an ammeter, and a battery. How much current flows
through the ammeter?
A.
B.
C.
D.
6.0 A
13.0 A
24.0 A
0.75 A
Show your work:
Part 5: Open Response – CHOOSE 1 of the following 2 questions and answer each part of it
OPTION 1:
A student rubs a balloon on her hair and the balloon acquires a negative charge.
a. Explain why the balloon acquires a negative charge.
b.
After the balloon is rubbed on the student's head, the student's hair stands out from her head. Explain
why this happens.
The student then brings the negatively charged balloon near another balloon that was charged in the
same way.
c.
Describe and explain what happens when the negatively charged balloon is brought near another
negatively charged balloon.
OPTION 2: A circuit with three identical light bulbs is shown in the diagram below.
a. Identify the symbol labeled J in the circuit.
b. Describe what each light bulb does in each of the following situations:

when switches 1 and 2 are open

when switches 1 and 2 are closed

when switch 1 is open and switch 2 is closed

when switch 1 is closed and switch 2 is open