PHYS 2426 – Engineering Physics II
DC Circuits Ranking Tasks
Leader: _________________________
Skeptic: _________________________
Recorder: __________________________
Encourager: ________________________
Materials
Laptop
Introduction
This activity is intended to help you develop intuitive reasoning about resistors connected in
series and parallel combinations. Particularly we will address the power dissipated by the
resistors.
In the following circuits, light bulbs are indicated as resistors. Not all blanks will be used in all
tasks.
1. a) For the following circuit predict the rank of the brightness of the light bulbs from brightest
to least bright. Assume all batteries are identical and ideal and if a resistance is not explicitly
shown, assume all light bulbs are identical. Place any ties in the same blank.
A
10Ω
B
10Ω
6vdc
C
10Ω
Brightest 1.____2.____3.____4.____5.____6.____ Least
or,
____They all have the same brightness
or,
____ It cannot be determined
b) Carefully explain your reasoning.
Check your answer by building the circuit with the PhET circuit construction kit, but only after
you have answered parts a) and b).
c) Reconcile any differences between your answer to parts a) and b) and what you observed in
the simulation.
d) On the back of this sheet, analyze the circuit and determine the current through, potential
across and power dissipated by each resistor
2. a) For the following circuit predict the rank of the brightness of the light bulbs from brightest
to least bright. Assume all batteries are identical and ideal and if a resistance is not explicitly
shown, assume all light bulbs are identical. Place any ties in the same blank.
A
10Ω
B
15Ω
6vdc
C
20Ω
Brightest 1.____2.____3.____4.____5.____6.____ Least
or,
____They all have the same brightness
or,
____ It cannot be determined
b) Carefully explain your reasoning.
Check your answer by building the circuit with the PhET circuit construction kit, but only after
you have answered parts a) and b).
c) Reconcile any differences between your answer to parts a) and b) and what you observed in
the simulation.
d) On the back of this sheet, analyze the circuit and determine the current through, potential
across and power dissipated by each resistor.
3. a) For the following circuit predict the rank of the brightness of the light bulbs from brightest
to least bright. Assume all batteries are identical and ideal and if a resistance is not explicitly
shown, assume all light bulbs are identical. Place any ties in the same blank.
6vdc
A
10Ω
B
10Ω
C
10Ω
Brightest 1.____2.____3.____4.____5.____6.____ Least
or,
____They all have the same brightness
or,
____ It cannot be determined
b) Carefully explain your reasoning.
Check your answer by building the circuit with the PhET circuit construction kit, but only after
you have answered parts a) and b).
c) Reconcile any differences between your answer to parts a) and b) and what you observed in
the simulation.
d) On the back of this sheet, analyze the circuit and determine the current through, potential
across and power dissipated by each resistor.
4. a) For the following circuit predict the rank of the brightness of the light bulbs from brightest
to least bright. Assume all batteries are identical and ideal and if a resistance is not explicitly
shown, assume all light bulbs are identical. Place any ties in the same blank.
B
10Ω
6vdc
A
10Ω
D
10Ω
E
10Ω
C
10Ω
F
10Ω
Brightest 1.____2.____3.____4.____5.____6.____ Least
or,
____They all have the same brightness
or,
____ It cannot be determined
b) Carefully explain your reasoning.
Check your answer by building the circuit with the PhET circuit construction kit, but only after
you have answered parts a) and b).
c) Reconcile any differences between your answer to parts a) and b) and what you observed in
the simulation.
d) On the back of this sheet, analyze the circuit and determine the current through, potential
across and power dissipated by each resistor.
5. a) For the following circuit predict the rank of the brightness of the light bulbs from brightest
to least bright. Assume all batteries are identical and ideal and if a resistance is not explicitly
shown, assume all light bulbs are identical. Place any ties in the same blank.
B
10Ω
6vdc
A
10Ω
D
10Ω
E
15Ω
C
15Ω
F
20Ω
Brightest 1.____2.____3.____4.____5.____6.____ Least
or,
____They all have the same brightness
or,
____ It cannot be determined
b) Carefully explain your reasoning.
Check your answer by building the circuit with the PhET circuit construction kit, but only after
you have answered parts a) and b).
c) Reconcile any differences between your answer to parts a) and b) and what you observed in
the simulation.
d) On the back of this sheet, analyze the circuit and determine the current through, potential
across and power dissipated by each resistor.