Download Unit 2 Test - hhs-snc1d

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Date: __________________
Unit 2 Test
SNC 1D
Part A:
Multiple Choice
Circle the best answer for each question.
/ 18 marks
1. Which of the following would be a good conductor?
a) Fur
b) Oxygen gas
c) Plastic
d) Aluminum
Metals are good conductors
2. Four 2V dry cells are connected in series. What would the voltage going through the
circuit be?
a) 2V
b) 4V
c) 8V
d) 42V
3. 4 light bulbs are connected in parallel. One of the bulbs is removed. What happens
to the other lights?
a) They stay on with the same brightness
b) They stay on but get brighter
Other bulbs get more electrons, same voltage
c) They stay on but get dimmer
d) They all go out
4. 4 light bulbs are connected in series. One of the bulbs is removed. What happens
to the other lights?
a) They stay on with the same brightness
b) They stay on but get brighter
c) They stay on but get dimmer
d) They all go out
Electrons don’t make it to other bulbs
5. What is the symbol for the SI unit for current?
a) V
b) A
The unit for current is the Ampere.
c) I
This is the symbol for current, but not the unit
d) Ω
6. What does “I” stand for?
a) Current
b) Voltage
c) Power
d) Resistance
7. Which of these equations summarizes Ohm's Law?
a) R = VI
b) R = I / V
c) R = V + I
d) R = V / I
8. A piece of fur is positively charged when;
a) It has an surplus of electrons
b) It has a deficiency of electrons
c) It is neutral
d) The gains electrons.
positive means fewer electrons
9. A wire that gives the electrons a path that bypasses (avoids) the load of a circuit is called a(n):
a) series circuit
b) closed circuit
c) open circuit
d) short circuit
10.Three ways for charging objects are:
a) friction, conduction and contact
b) friction, contact and induction
c) conduction, induction and contact
d) none of the above
11. In general, electrocution accidents occur when:
a) humans are negatively charged
b) humans are positively charged
c) humans give electrons a path to the ground
d) humans touch metal
12. To measure the current going through a circuit:
a) an ammeter is inserted in series with the circuit
b) an ammeter is connected in parallel to the circuit
c) a voltmeter is inserted in series with the circuit
d) a voltmeter is connected in parallel with the circuit
13. To measure the voltage loss in a resistor:
a) an ammeter is inserted in series with the resistor
b) an ammeter is connected in parallel to the resistor
c) a voltmeter is inserted in series with the resistor
d) a voltmeter is connected in parallel with the resistor
14. When two 3V dry cells are connected in parallel:
a) the combined voltage is 6V
b) the combined voltage is 3V
c) the combined voltage is 1.5V
d) none of the above
15. A 840W hairdryer is plugged into a 120V outlet. The current going through the hairdryer is:
a) 120W
c) 30A
b) 7A
I = P/V
d) 50Ω
16. Another word for potential difference is:
a) voltage
b) current
c) amperage
d) resistance
17. When a resistor is added in parallel to a circuit, the total resistance of the circuit
a) increases
c) stays the same
b) decreases
d) none of the above
18. When a resistor is added in series to a circuit, the total resistance of the circuit
a) increases
c) stays the same
b) decreases
d) none of the above
Part B:
Short Answers / Problems
/13 marks
Use these formulas to solve. Show all your work. Include units.
Q
E
E
V

IR
V

I

P

P

IV
Q
t
t
1. Calculate the voltage loss of a food blender that has a resistance of 65 ohms and has a
current of 1.85 amps. (3 marks)
V = IR
V = (1.85)(65)
V = 120.25 Volts
2. Calculate the current flowing through a toaster oven that is plugged into a 120 volt outlet
and has a resistance of 9.2 ohms. (3 marks)
V
I
I
I
= IR
= V/R
= 120/9.2
= 13 Amperes
3. How much energy is consumed by a 450W computer left on for 2 hours? (3 marks)
P = E/t
E=Pxt
E = (450)(7200)
E = 3240000 J
Convert time to seconds
t = 2 hours x 60 minutes x 60 seconds = 7200 s
4. Convert your answer in the previous question to kWh. [1 mark]
1 kWh = 3 600 000 J
From previous question E = 3 240 000 J
E = 3240000 / 3 600 000 = 0.9kWh
Another solution:
450 Watt x 2 hours
= 900 Watt hours
= 0.900 kiloWatt hours
5. Calculate the power rating of a shaver that operates on a voltage of 6 V and has a
resistance of 25Ω. (3 marks)
P = IV but we don’t know I
Use V = IR to find current first:
V = IR
I = V/R
= 6 / 25
= 0.24 Ampere
Now P = IV
P=IV
P = (0.24)(6)
P = 1.44 Watts
Part E: Thinking and Inquiry
/13 marks
Four friends challenge each other to a run around a park. Tommy has four granola bars in
his backpack, so he gives each runner one bar and some water. Full of energy, they then
set off on their run, running over a big hill, then a hill only half as big, and then around
some trees and back to their starting point. When they return they flop down on the
ground, exhausted.
This story can be compared to the workings of an electric circuit. With that in mind,
answer the following questions:
1.
a)
What would be the:
“resistors” in this circuit?
Hills
b)
“charges” in this circuit?
Runners
2.
How many runners would a bystander count going by:
a)
b)
c)
d)
at the beginning of the race?
at the top of the first hill?
at the top of the second hill?
arriving back at the start?
3.
If each of the bystanders in question #2 saw all the runners go by in a space of 4
seconds , what would the value of the “current” in this circuit be? Give a number
and units.
4
4
4
4
In electricity, current is number of charges per unit of time.
Here the “current” is 4 runners in 4 seconds, equal to 1 runner/second
In other words, 1 runner goes by any point in the circuit every second.
4.
What would represent the “battery” of this circuit? What is the value of the
“voltage” of this battery be?
Tommy is the battery. He gives a “voltage” of 1 granola bar per runner.
5.
What is the amount of “voltage loss” in the first hill? Give a value and units.
The first hill uses up 2/3 of a granola bar.
6.
What is the amount of “voltage loss” in the next hill? Give a value and units.
The second hill uses up 1/3 of a granola bar.
7.
What would happen if they repeated the race but had twice as much energy at the
start?
They would run it faster, in less time.
8.
What would happen if they repeated the race but the second hill was as big as the
first?
They would run it slower, taking a longer time