Download Review Exam3

PHYS 100 Introductory Physics
Sample Exam 3
Formulas:
Charge of 1 electron  - 1.6 x 10 -19 Coulomb
Charge of 1 proton   1.6 x 10 -19 Coulomb
Electric Field 
Force
Charge
Electric Potential 
Current 
Electric Potential Energy
Charge
Voltage
Resistance
Power  Current x Voltage
Section A: All questions in this section are mandatory.
1. One difference between moving and stationary charges is that
a. Moving charges exert only magnetic forces, while stationary charges exert both electric
and magnetic forces.
b. Moving charges exert both electric and magnetic forces, while stationary charges exert
only electric forces.
c. Moving charges exert only magnetic forces, while stationary charges exert only electric
forces.
d. Moving charges exert both electric and magnetic forces, while stationary charges exert
neither electric nor magnetic forces.
2. What does a neutral atom become if it loses an electron?
a.
b.
c.
d.
A superconductor
A negatively charged ion
A positively charged ion
It stays neutral
3. Two 20-Ohm resistances are connected in series. The total resistance in the circuit is
a.
b.
c.
d.
equal to 20 Ohms
less than 20 Ohms
greater than 20 Ohms
it depends on the voltage
4. A simple circuit is shown. How much current is flowing
in this circuit?
a.
b.
c.
d.
12 Amperes
2.5 Amperes
360 Amperes
0.4 Amperes
12 Volt Battery
30 Ohm Resistance
5. What is the direction of current flow in the circuit of question #4 above?
a.
b.
c.
d.
Counter Clockwise
Clockwise
Both a and b
Cannot be determined from the given information
6. Electromagnetic induction occurs in a coil when there is a change in
a.
b.
c.
d.
voltage in the coil
the coil’s polarity
electric field intensity in the coil
magnetic field intensity in the coil
7. A 120-Volt outlet has a 20-Ampere fuse connected in series with it. What is the maximum
power that can be delivered by this outlet?
a.
b.
c.
d.
2400 Watts
120 Watts
6 Watts
1200 Watts
8. A neutral atom has equal number of
a.
b.
c.
d.
protons and neutrons
electrons and protons
electrons and neutrons
none of these
9. A +2 C charge is brought to a position that is midway between a -3 C charge and a -2 C charge.
If the negative charges were fixed (unable to move), in what direction would the positive charge
go?
a.
b.
c.
d.
Up (away from both charges).
Down (away from both charges).
Right (toward the -2 C charge).
Left (toward the -3 C charge).
+2 C
-3 C
-2 C
10. Which of the following is a unit of electric charge?
a. Coulomb
b. Volt
c. Ohm
d. Ampere
11. If a steady magnetic field exerts a force on a moving charge, that force is directed
a.
b.
c.
d.
perpendicular to the direction of the field
in the direction of motion of the charge
in the direction of the field
opposite to the direction of the field
12. A quantity that measures opposition to the flow of charge is
a. current
b. voltage
c. resistance
d. electric field
13. A device that transforms mechanical energy into electrical energy is a
a. magnet
b. transformer
c. generator
d. motor
14. Which of the following materials conduct electricity with the greatest amount of resistance?
a. Superconductors
b. Semiconductors
c. Metals
d. Insulators
15. The Coulomb force (also called the electrostatic force) depends on the
a.
b.
c.
d.
magnitude of electric charges
separation distance between electric charges
both of these
none of these
16. The energy per Coulomb of charge supplied by a battery is its
a. electric field
b. voltage
c. current
d. resistance
17. As more lamps are put into a series circuit, the overall current in the power source
a.
b.
c.
d.
remains the same
decreases
increases
all of the above are possible
18. An electric current is formed by,
a.
b.
c.
d.
Flow of neutral atoms.
Flow of negative charges only.
Flow of positive charges only.
Flow of positive or negative charges.
19. In a circuit, a 4 Coulomb charge goes through a potential difference of 16 Volts. How much
energy did the charge lose during this process?
a. 4 J
b. 16 J
c. 0.25 J
d. 64 J
20. The element of an electric oven is designed to produce 2000 Watts of heat when connected to a
110-Volt source. Calculate the resistance of the heating element. You may assume that this element is
100% efficient, that is, it converts all of the electrical energy into heat.
a. 6 ohms
b. 0.06 ohms
c. 18.2 ohms
d. 0.17 ohms
21. Calculate the cost of operating a 750-Watt appliance for 48 hours. The cost of energy is 10 cents
per kilowatt-hour.
a. $36.00
b. $3.60
c. $15.63
d. $1.56
22. A 3-Coulomb charge jumps from 68 Volts to 50 Volts. In this process the charge
a.
b.
c.
d.
gains 18 Joules of energy
loses 54 Joules of energy
loses 18 Joules of energy
loses 6 Joules of energy
23.A charge moving through a magnetic field experiences a force that is always
a.
b.
c.
d.
in the same direction as the field
perpendicular to the direction of the field
opposite to the direction of the field
none of the above
24.Two light bulbs are connected in series. What happens to the brightness of the other bulb if you
short-circuit one of them?
a.It gets dimmer
b. It gets brighter
c. It turns off completely
d. There is no change in brightness
25. A typical 12 V battery has a rating of 60Ah. How much charge in Coulombs is in 60Ah?
a. 3600 C
b. 216,000 C
c. 36 C
d. 720 C