Reading Quiz
• A light bulb is connected to a battery so that
current flows through the bulb, which gives
off light. Choose the correct statement:
• The amount of current going into the bulb equals
the current leaving the bulb.
• The amount of current entering the bulb is
greater than the amount of current leaving the
bulb.
• The bulb is converting electric charge into light.
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Chapters 10,11,12,13,14,15
Summary of electric circuits:
1. The amount of current is the same at every place in a series
circuit; I=q/t.
2. The power provided by the battery (P=IDV) is exactly
equal to the power dissipated in the resistors (P=I2R).
3. Ohm’s Law applies to resistors: DV=IR
4. Series circuit: effective R = R1 + R2 + R3
5. Parallel circuit: effective R is
1
1 1
1
 

Reff R1 R2 R3
Fig. 13.3
Fig. 13.1
Fig. 13.2
Fig. 13.4
Summary 2
Ohm’s Law applies to resistors: DV=IR
Battery increases energy of
charges (DPE); voltage on
battery is called “EMF”.
I
V
EMF
volts
R
This amount of energy is
expended in the resistor.
For a given battery (V) and
resistor (R), the current is
given by Ohm’s Law:
DV=IR
The unit of resistance is an Ohm.
Fig. 13.6
Fig. 13.7
Fig. 13.5
Lecture Quiz 26 - Question 1:
A simple battery does which of the following:
A. It creates charges.
B. It does work on charges.
C. It creates energy.
Series Resistance
EMF= DV1 + DV2 + DV3
OR
V
EMF
V = IR1 + IR2 + IR3
R1
R2
volts
R3
= I(R1 + R2 + R3)
= I Rseries
Where Rseries = R1 + R2 + R3
Is the voltage drop the same across all three resistors?
Is the current the same through all three resistors?
Fig. 13.9
Exercise 9
What is the total
resistance of this
circuit?
1.) 66 ohms
2.) 60 ohms
3.) 54 ohms
4.) 25 ohms
5.) 15 ohms
Exercise 9
What is the current
that flows in this
circuit?
1.)10 amps
2.) 1 amp
3.) 0.1 amp
4.) 0.3 amp
5.) 0.03 amps
Fig. 13.10
Parallel Resistors
Effective resistance
1
1 1
1
 

Reff R1 R2 R3
V
EMF
volts
1
2
3
Where
V = I Reffective
How much current flows through the three resistors?
Is the voltage drop the same for all three resistors?
Exercise 12
What is the total resistance of this circuit?
1.) 72 ohms
2.) 24 ohms
3.) 12 ohms
4.) 8 ohms
5.) 2 ohms
A
.
What is the current that flows in this
circuit at point A?
1.)288 amps
2.) 1.5 amp
3.) 0.1 amp
4.) 0.5 amp
5.) 0.03 amps
B
What is the current that
flows in this circuit at
point B?
1.)288 amps
2.) 1.5 amp
3.) 0.1 amp
4.) 0.5 amp
5.) 0.03 amps
.
By placing all electric items in parallel
they receive the same voltage
By placing electrical items in series
they receive the same current
A volt meter has a high resistance so take very little current
Fig. 13.13
An Amp meter has very little resistance so take
very little voltage
Summary of electric circuits:
1. The amount of current is the same at every place in a
circuit; I=q/t.
2. The power provided by the battery (P=IDV) is exactly
equal to the power dissipated in the resistors (P=I2R).
3. Ohm’s Law applies to resistors: DV=IR
4. Series circuit: effective R = R1 + R2 + R3
5. Parallel circuit: effective R is
1
1 1
1
 

Reff R1 R2 R3
Question 14
The power provided by the battery (P=IDV) is exactly equal
to the power dissipated in the resistors (P=I2R).
Power P= work/time
Power=DPE/t
=qDV/t
=IDV
=IV
For an “ohmic” resistor, V=IR, so P = I2R
Lecture Quiz #26
Question 2
Consider a standard flashlight which is turned on.
A. The batteries create electrons, which get used up
in the light bulb.
B. Energy is created in the batteries, which is
destroyed in the light bulb.
C. The power used up by the light bulb originates in
the batteries.
D. The light bulb converts electrons into light.
Lecture Quiz: Question 3
How much current I runs through this circuit:
A. 0.25 Amps
B. 0.375 A
3V
4W
4W
C. 0.67 A
D. 1.50 A
E. 2.25 A
Lecture Quiz: Question 4
For three resistors in parallel, choose the correct statement:
A. The current and the voltage
across all three are the same.
EMF
volts
1
2
3
B. The voltage drop and the
power dissipated across all
three are the same.
C. The energy given up per
electron is the same for all
three.
D. The current through one
resistor is the same as the
current through the battery.
The amount of current is the same at every place in a (singleloop) circuit; I=q/t.
I
Battery
Light
Bulb
I
I
What does the battery do?
I
Where does the light
energy come from?
Why do batteries burn
out?