PHY 112 EXAM 1 MULTIPLE CHOICE QUESTIONS AND
VERIFIED ANSWERS
Two electrons are 20.0mm apart at closest approach. What is the magnitude of the
maximum electric force that they exert on each other? - Answers - 5.8x10^-25 N
Two stationary point charges q1 and q2 are shown in the figure along with a sketch of
some field lines representing the electric field produced by them. What can you deduce
from the sketch? - Answers - q1 is negative and q2 is positive; the magnitude of q1 is
less than the magnitude of q2
For the graph shown in the figure, what physical quantity does the slope of the graph
represent for the ohmic material - Answers - 1/(resistance)
An ideal parallel-plate capacitor has a capacitance of C. If the area of the plates is
doubled and the distance between the plates is halved, what is the new capacitance? -
Answers - 4C
The plates of a parallel-plate capacitor are maintained with constant voltage by a battery
as they are pulled apart. What happens to the strength of the electric field between the
plates during this process? - Answers - it decreases
When a dielectric material is introduced between the plates of a parallel-plate capacitor
and completely fills the space, the capacitance increases by a factor of 4. What is the
dielectric constant of the material that was introduced? - Answers - 4
At a distance d from a point charge Q, the energy density in its electric field is u. If we
now go to a distance d/2 from the charge, what is the energy at the new location? -
Answers - 16u
A hydrogen atom consists of a proton and an electron if the orbital radius of the electron
increases, the electric potential energy of the electron due to the proton - Answers -
increases
The plates of a parallel-plate capacitor are maintained with constant potential by a
battery as they are pulled apart. During this process, the amount of charge on the plates
- Answers - must decrease
If the length and diameter of a wire of circular cross section are both tripled, the
resistance will be - Answers - 1/3 of what it originally was
VERIFIED ANSWERS
Two electrons are 20.0mm apart at closest approach. What is the magnitude of the
maximum electric force that they exert on each other? - Answers - 5.8x10^-25 N
Two stationary point charges q1 and q2 are shown in the figure along with a sketch of
some field lines representing the electric field produced by them. What can you deduce
from the sketch? - Answers - q1 is negative and q2 is positive; the magnitude of q1 is
less than the magnitude of q2
For the graph shown in the figure, what physical quantity does the slope of the graph
represent for the ohmic material - Answers - 1/(resistance)
An ideal parallel-plate capacitor has a capacitance of C. If the area of the plates is
doubled and the distance between the plates is halved, what is the new capacitance? -
Answers - 4C
The plates of a parallel-plate capacitor are maintained with constant voltage by a battery
as they are pulled apart. What happens to the strength of the electric field between the
plates during this process? - Answers - it decreases
When a dielectric material is introduced between the plates of a parallel-plate capacitor
and completely fills the space, the capacitance increases by a factor of 4. What is the
dielectric constant of the material that was introduced? - Answers - 4
At a distance d from a point charge Q, the energy density in its electric field is u. If we
now go to a distance d/2 from the charge, what is the energy at the new location? -
Answers - 16u
A hydrogen atom consists of a proton and an electron if the orbital radius of the electron
increases, the electric potential energy of the electron due to the proton - Answers -
increases
The plates of a parallel-plate capacitor are maintained with constant potential by a
battery as they are pulled apart. During this process, the amount of charge on the plates
- Answers - must decrease
If the length and diameter of a wire of circular cross section are both tripled, the
resistance will be - Answers - 1/3 of what it originally was
