Benchmark 1 Review
Spring 2014
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Protons have what type of charge?
Answer: positive
Electrons have what type of charge?
Answer: negative
Like charges ______, and unlike charges _____.
Answer: repel, attract
According to Coulomb’s Law, as the distance between two charges is halved, the electric force is
_______.
Answer: quadrupled
Is electric force a vector or scalar quantity?
Answer: vector
Which force is stronger; electrostatic force or gravitational force?
Answer: electrostatic
What is the SI unit for charge? Answer: coulomb
What is the SI unit for electric potential difference?
Answer: volts
What is the SI unit for electric field strength?
Answer: N/C
What is the name of the device used to detect electric charges?
Answer: electroscope
Touching an object to Earth to eliminate excess charge is called what? Answer: grounding
Charging an object due to direct contact between the objects is called charging by _____.
Answer: conduction
Charging an object without any direct contact between objects is called charging by _____.
Answer: induction
A charged balloon will stick to a wall due to ____of charges.
Answer: polarization
A negatively charged balloon attracts another balloon. What conclusion can be drawn about the
2nd balloon?
Answer: either positive or neutral
A material that allows electrons to flow freely throughout the material is called a _____.
Answer: conductor
A force of 14 N exists on a charge which is 2.1 x 10-9 C. What is the magnitude of the electric
field?
Answer: 6.7 x 109 N/C
A proton and electron are held 1 m apart and then released. What happens to the force
between them?
Answer: it becomes stronger
Give three examples of static electricity.
Answer: lightning, balloon rubbed in hair, socks
in the dryer sticking together, etc
Do electric field lines point toward or away from negative charges?
Answer: toward
Name two materials that are good insulators. Answer: wood, plastic, cloth, etc
A plastic tube rubbed with wool will acquire what charge?
Answer: negative
Lightning forms when the charges within the cloud become separated. In what region of the
cloud are the negative charges located? Answer: at the bottom of the cloud
A 4.5 x 109 C charge is located 3.2 m from a 2.8 x 109 C charge. Find the magnitude of the
electrostatic force between the two charges. Answer: 1.1 x 1028 N
25. What is the electric field 35 m from a charge of 3.0 C? Answer: 2.2 x 107 N/C
Electricity
1. What is the formula for Ohm’s Law? Answer: V=IR
2. What is the formula for Electrical Power? Answer: P=IV
3. The amount of charge that flows through a circuit is called the _____.
Answer: current
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The SI unit for resistance is the _____.
Answer: ohm
Current is measured with what unit?
Answer: ampere
A circuit consisting of only one path is what type?
Answer: series
In what type of circuit will all lights go out if one goes out?
Answer: series
What variable is the same everywhere in a parallel circuit?
Answer: voltage
What variable is the same everywhere in a series circuit?
Answer: current
In what type of circuit is the total resistance smaller than any single resistor in the circuit?
Answer: parallel
11. Name three factors that affect the resistance of a wire.
Answer: thickness, material,
temperature, or length
12. As temperature increases, resistance _____.
Answer: increases
13. As length increases, resistance _____.
Answer: increases
14. A 100 W light bulb is connected to a 120 V electric line. What is the current that the light bulb
draws?
Answer: 0.8 A
15. What is the effect on the current in a simple circuit if both the voltage and the resistance are
reduced by half?
Answer: no change
16. How much electric energy is delivered to a 60 W light bulb if the bulb is left on for 2.5 hours?
Answer: 540, 000 J
17. What is the equivalent resistance of a 3 ohm, 12 ohm, and 4 ohm resistor wired in parallel?
Answer: 1.5 ohm
18. In what type of circuit does the current increase as more devices are added? Answer: parallel
19. A lamp is connected to a battery of 50 V, and the current that flows through the circuit is 2 A.
What is the resistance of the lamp?
Answer: 25 ohms
20. A 2 ohm and 5 ohm resistor are connected in parallel to each other and in series with a 10 V
battery. What is the current through the 5 ohm resistor?
Answer: 2 A
21. Three identical resistors are connected in series to a 9 V battery. What is the voltage drop
across each resistor? Answer: 3 V
22. A 4 Ω and 2 Ω resistor connected in parallel are connected in series to a 12 V battery. What is
the voltage across the 4 Ω resistor?
Answer: 12 V
23. What device is used to measure the current flowing in a circuit?
Answer: ammeter
24. Nina connects eight 12 ohm lamps in series. What is the total resistance? Answer: 96 ohms
25. In circuit 1, two identical light bulbs are connected in parallel to each other and in series
with a 12 V battery. In circuit 2, the same two light bulbs are connected in series with the
12 V battery. Which circuit produces more light?
Answer: circuit 1
26. In a parallel circuit, what happens to the current in the remaining bulbs when one bulb is
removed?
Answer: it is unchanged
27. What is the equivalent resistance of a 30 ohm and a 20 ohm resistor connected in parallel?
Answer: 12 ohms
28. How much voltage is required to make 4 A flow through a 12 ohm resistor? Answer: 48 V
29. A battery does 18 J of work on 10 C of charge. What voltage does the battery supply? omit
30. A 35 ohm, 55 ohm, and 85 ohm resistor are connected in parallel. The resistors are connected to
a 35 V battery.
a. What is the equivalent resistance of the parallel combination? Answer: 17 ohms
b. What is the current through each resistor? Answer: I1= 1 amp; I2 = 0.64 amps ; I3= 0.41
amps