Download E - umdberg

Clicker Questions for NEXUS/Physics
Capacitors
Where do you expect the E field
to point at the position A?
A
A. It should point to the left.
B. It should be essentially 0.
C. It should point to the right.
B
C
NEXUS/Physics Clicker Questions
Two large parallel sheets of charge are
separated by a distance d , small compared
to the size of the sheets. The distance d is
small enough that the sheets can be treated
as if they were infinite in extent.
Where do you expect the E field
to point at the position B?
A
A. It should point to the left.
B. It should be essentially 0.
C. It should point to the right.
B
C
NEXUS/Physics Clicker Questions
Two large parallel sheets of charge are
separated by a distance d , small compared
to the size of the sheets. The distance d is
small enough that the sheets can be treated
as if they were infinite in extent.
Where do you expect the E field
to point at the position C?
A
A. It should point to the left.
B. It should be essentially 0.
C. It should point to the right.
B
C
NEXUS/Physics Clicker Questions
Two large parallel sheets of charge are
separated by a distance d , small compared
to the size of the sheets. The distance d is
small enough that the sheets can be treated
as if they were infinite in extent.
NEXUS/Physics Clicker Questions
If the sheets can be treated as if they were infinitely large,
which of the following graphs might serve as a graph of the
x-component of the electric field as a function of the
coordinate x along the dotted line?
NEXUS/Physics Clicker Questions
If the sheets can be treated as if they were infinitely large,
which of the following graphs might serve as a graph of the
electric potential as a function of the coordinate x along the
dotted line?
A. The potential difference
would increase.
B. The potential difference
would decrease.
C. The potential difference
would stay the same.
+
+
+
+
+
+
V
E
–
–
–
–
–
–
–
0
NEXUS/Physics Clicker Questions
What would happen to the voltage
if you first disconnected the battery
and then pulled the plates
further apart?
+
A. The potential difference
would increase.
B. The potential difference
would decrease.
C. The potential difference
would stay the same.
+
+
+
+
+
+
V
–
–
–
–
–
–
–
0
NEXUS/Physics Clicker Questions
What would happen to the voltage
if you stayed connected to the battery
and then pulled the plates
E
further apart?
+
A. The charge on each plate
would increase.
B. The charge on each plate
would decrease.
C. The charge on each plate
would stay the same.
+
+
+
+
+
+
V
–
–
–
–
–
–
–
0
NEXUS/Physics Clicker Questions
What would happen to the voltage
if you stayed connected to the battery
and then pulled the plates
E
further apart?
+
A.
B.
C.
D.
E.
F.
Stays the same
Bigger by ~X2
Bigger but not by ~X2
Smaller by ~X2
Smaller but not by ~X2
Can’t tell
NEXUS/Physics Clicker Questions
Cap #1 is charged by connecting it
to a battery. Cap #2 is not charged.
C#1 is disconnected from the battery
and connected to C#2. How does
the magnitude of the E field
in C#1 change?
Three capacitors 1, 2, 3 are connected to identical
batteries so they each have the same ΔV.
Their plate areas and separations are as follows:
A2 = 2 A1 = 2 A3; d1 = d2 = 2d3.
A.
B.
C.
D.
E.
F.
G.
E2 = E3 > E1
E3 > E1 = E2
E2 > E1 > E3
E2 > E1 = E3
E1 = E2 > E3
E1 = E2 = E3
Other
NEXUS/Physics Clicker Questions
How do the E fields inside them rank?
Three capacitors 1, 2, 3 are connected to identical
batteries so they each have the same ΔV.
Their plate areas and separations are as follows:
A2 = 2 A1 = 2 A3; d1 = d2 = 2d3.
A.
B.
C.
D.
E.
F.
G.
Q 2 = Q3 > Q1
Q 3 > Q1 = Q2
Q2 > Q1 > Q3
Q 2 > Q1 = Q3
Q 1 = Q2 > Q3
Q 1 = Q2 = Q3
Other
NEXUS/Physics Clicker Questions
How do the net charges on them rank?
Three capacitors 1, 2, 3 are connected to identical
batteries so they each have the same ΔV.
Their plate areas and separations are as follows:
A2 = 2 A1 = 2 A3; d1 = d2 = 2d3.
A.
B.
C.
D.
E.
F.
G.
Q 2 = Q3 > Q1
Q 3 > Q1 = Q2
Q2 > Q1 > Q3
Q 2 > Q1 = Q3
Q 1 = Q2 > Q3
Q 1 = Q2 = Q3
Other
NEXUS/Physics Clicker Questions
How do the positive charges on their top plate rank?
Three capacitors 1, 2, 3 are connected to identical
batteries so they each have the same ΔV.
Their plate areas and separations are as follows:
A2 = 2 A1 = 2 A3; d1 = d2 = 2d3.
A.
B.
C.
D.
E.
F.
G.
ΔV2 = ΔV3 > ΔV1
ΔV3 > ΔV1 = ΔV2
ΔV2 > ΔV1 > ΔV3
ΔV2 > ΔV1 = ΔV3
ΔV1 = ΔV2 > ΔV3
ΔV1 = ΔV2 = ΔV3
Other
NEXUS/Physics Clicker Questions
How do the voltage drops across their plates rank?
• Suppose we:
• Close A for a few seconds
• Open A
• Close B
A.
B.
C.
D.
E.
F.
It stays off.
It stays on after you close A
It stays on after you close B
It flashes when you close A
It flashes when you open A
It flashes when you close B
B
A
NEXUS/Physics Clicker Questions
• What happens
to the bulb?
A.The stored electrical energy
increases.
B.The stored electrical energy remains
the same.
C.The stored electrical energy
decreases.
NEXUS/Physics Clicker Questions
Suppose the capacitor is connected to
the battery. The plates remain
connected and an insulating slab of
dielectric constant 𝜅 ( > 1) is slid
between the plates. What happens to
the electrical energy stored in the
capacitor as a result of inserting the
insulating slab?