Download wk.22.tuesday.hmwk.equivalent resistance

wk.22.tuesday.hmwk.equivalent resistance
Requivalent _ series = R1 + R2 + R3 + ...
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R1 R2 R3
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Resistors in series divide voltage
Resistors in parallel divide current
1. Two 100 ohm resistors are placed in series. What is the equivalent resistance of this
network?
2. Two 100 ohms resistors are placed in parallel. what is the equivalent resistance of this
network?
3. Two 100 ohm resistors are placed in series and then connected to a 10 V battery.
What is the total current in the circuit?
4. Two 100 ohm resistors are connected in parallel and then connected to a 10 volt
battery. What is the total current in this circuit?
5. One 100 ohm resistor is connected to a 10 V battery. What is the current through this
resistor?
6. Two 100 ohm resistors are placed in parallel and then connected to a 10 V battery.
What is the current through each of the 100 ohm resistors?
7. Three 100 ohm resistors are connected in parallel and then connected to a 10 volt
battery. What is the current through each of the 100 ohm resistors?
8. Five 100 ohm resistors are connected in parallel. What is the equivalent resistance of
this network?
9. Ten 100-ohm resistors are connected in parallel. What is the equivalent resistance of
this network?
10. A 10,000 ohm resistor is connected in parallel with a 100 ohm resistor. what is the
equivalent resistance of this network?
11. A 1,000,000 ohm (1 mega-ohm) resistor is placed in parallel with a 10 ohm resistor.
What is the equivalent resistance of this network?
12. A watt is equal to a
A. volt per amp
D. a volt•ohm
B. a joule per second
C. A newton per second
13. An ampere is equal to
A. coulomb• second B. coulomb / second C. A volt•ohm
D. one ohm
per vol
14. A 1000 watt appliance is left on for 1 hour. How much energy is used?
A. 1000 joules
D. 6000 joules
B. 6.0 e4 joules
C. 3.6 e 6 joules
15. What is the equivalent resistance of the following circuit? All resistors are 100 Ω.
i. 100 Ω
j. 33 Ω
k. 16.7 Ω
l. 50 Ω
answers
1. 200 ohms
2. 50 ohms 3. 0.05 amps (50 mA) (10V/200 ohms) 4. 0.20 amps (200 mA)
parallel circuits have higher current
5. 0.1 A or 100 mA
6. The total current through the circuit is 0.20 amps. resistors in parallel divide current and since these resistors are the same value
they divide the current equally. Therefore each resistor carries 0.10 amps or 0.1 mA. Notice that this is the same current that they
would carry if they were connected to the battery by themselves.
7. 0.1 A or 100 mA
8. 20 ohms (When all the resistors are the same value and you place them in parallel then just divide the value of the resistor by the
number of resistors you have)
9. 10 ohms (you’re an electrical engineer already)
10. 99.9 ohms (when tow resistors are placed in parallel and one is much larger than the other, the equivalent resistance is just slightly
less (basically equal to) the resistance of the smaller resistance.
11. 10 ohms
12. B
13. A
14. C (this is called a kilowatt hour)
15. each of the three sub-networks is simply three 100 ohm resistors in parallel. Therefore each of these sub networks has an
equivalent resistance of 33.3 ohms.
Now these three 33.3 ohm networks are in series with each other, thus the equivalent resistance of the entire network is the sum of
these, or 100 ohms.