Honors Physics
Basic Electric Circuits #1
Resistances in Series, Parallel, and Series–Parallel Combinations
1.
MC Which of the following quantities must be the same for resistors in series? (a) voltage, (b) current, (c) power, (d) energy.
2.
MC Which of the following quantities must be the same for resistors in parallel? (a) voltage, (b) current, (c) power, (d) energy.
3.
MC Two resistors (A and B) are connected in series to a 12-V battery. Resistor A has 9 V across it. Which resistor has the least
resistance? (a) A, (b) B, (c) both have the same, (d) can’t tell from the data given
4.
MC Two resistors (A and B) are connected in parallel to a 12-V battery. Resistor A has 2.0 A in it and the total current in the
battery is 3.0 A. Which resistor has the most resistance? (a) A, (b) B, (c) both have the same, (d) can’t tell from the data given.
5.
MC Two resistors (one with a resistance of 2.0  and the other with 6.0  resistance) are connected in parallel to a battery.
Which one produces the most joule heating? (a) 2.0 , (b) 6.0 , (c) both produce the same, (d) can’t tell from the data
given.
6.
MC Two lightbulbs (bulb A has a rating of 100 W at 120 V and B has a rating of 60 W at 120 V) are connected in series to a
wall socket at 120 V. Which one produces the most light? (a) A, (b) B, (c) both produce the same, (d) can’t tell from the data
given.
7.
CQ Are the voltage drops across resistors in series generally the same? If not, under what circumstance(s) could they be the
same?
8.
9.
CQ Are the currents in resistors in parallel generally the same? If not, under what circumstance(s) could they be the same?
CQ If a large resistor and a small resistor are connected in series, will the effective resistance be closer in value to that of the
large resistance or the small one? What if they are connected in parallel?
10.
CQ Lightbulbs have a power output marked on them by the manufacturer. For example, a 60-W light bulb assumes the bulb is
connected to a 120-V source. Suppose you have two bulbs. One labeled 60 W is followed by a 40 W bulb in series to a 120-V
source. Which one glows the brightest? Why? What happens if you switch the order of the bulbs? Are either of them at full
power rating? Explain. see ISM
11.
CQ Three identical resistors are connected to a battery. Two are wired in parallel, and that combination is followed in series by
the third resistor. Which resistor(s) has (a) the largest current, (b) the largest voltage, and (c) the largest power output?
12.
CQ Three resistors have values of 5 , 2 , and 1 . The first one is followed in series by the last two wired in parallel. When
this arrangement is connected to a battery, which resistor(s) has (a) the largest current, (b) the largest voltage, and (c) the largest
power output?
13.
 Three resistors that have values of 10 , 20 , and 30 , respectively, are to be connected. (a) How should you connect
them to get the maximum equivalent resistance, and what is this maximum value? (b) How should you connect them to get the
minimum equivalent resistance, and what is this minimum value?
14.
 Two identical resistors (R) are connected in series and then wired in parallel to a 20- resistor. If the total equivalent
resistance is 10 , what is the value of R?
15.
 Two identical resistors (R) are connected in parallel and then wired in series to a 40- resistor. If the total equivalent
resistance is 55 , what is the value of R?
16.
IE  (a) In how many different ways can three 4.0- resistors, be wired: (1) three, (2) five, or (3) seven? (b) Sketch the
different ways you found in part (a) and determine the equivalent resistance for each. ISM
17.
 Three resistors with values of 5.0 , 10 , and 15 , respectively, are connected in series in a circuit with a 9.0-V battery.
(a) What is the total equivalent resistance? (b) What is the current in each resistor? (c) At what rate is energy delivered to the
15- resistor
18.
 Find the equivalent resistances for all possible combinations of two or more of the three resistors in Exercise 17. see ISM
19.
 Three resistors with values 1.0 , 2.0 , and 4.0 , respectively, are connected in parallel in a circuit with a 6.0-V battery.
What are (a) the total equivalent resistance, (b) the voltage across each resistor, and (c) the power delivered to the 4.0-
resistor?
20.
IE  (a) If you had only an infinite supply of 1.0- resistors, what is the minimum number of resistors required to make an
equivalent resistance of 1.5  : (1) two, (2) three, or (3) four? (b) Describe or show by a sketch how the resistors should be
connected.
Equation for #20
RT =
𝑹𝟏 𝑹𝟐
𝑹𝟏 +𝑹𝟐
( only for two parallel resistors)