Phys 202- Exam 1 updated study guide
actual questions and CORRECT answers
Two charged balls are repelling each other as they hang from the ceiling. What can you say
about their charges?
a) one is positive, the other is negative
b) both are positive
c) both are negative
d) both are positive and negative - CORRECT ANSWER d) both are positive and
negative
When you rub a plastic rod with fur, the plastic rod becomes negatively charged and the fur
becomes positively charged. As a consequence of rubbing the rob with the fur,
a) the rod and fur both gain mass
b) the rod and fur both lose mass
c) the rod gains mass and the fur loses mass
d) the rod loses mass and the fur gains mass
e) none - CORRECT ANSWER c) the rod gains mass and the fur loses mass
What is the magnitude of the force F2?
a) 1.0 N
b) 1.5 N
c) 2.0 N
d) 3.0 N
e) 6.0 N - CORRECT ANSWER d) 3.0 N
If we increase one charge to 4Q, what is the magnitude of F1?
a) 3/4 N
, b) 3.0 N
c) 12 N
d) 16 N
3) 48 N - CORRECT ANSWER c) 12 N
Two balls with charges +Q and +4Q are fixed at a separation distance of 3R. Is it possible to
place another charged ball Q0 on the line between the two charges such that the net force on
Q0 will be zero?
a) yes, but only if Qo is positive
b) yes, but only if Qo is negative
c) yes, independent of the sign (or value) of Qo
d) no, the net force can never be zero - CORRECT ANSWER c) yes, independent of
the sign (or value) of Qo
When two point charges are a distance d apart, the electric force that each one feels from the
other has a magnitude F. In order to make this force twice as strong, the distance would have
to be changed to
a) 2d
b)square root 2 times d
c) d/square root 2
d) d/2
e) d/4 - CORRECT ANSWER c) d/square root 2
The figure shows a Gaussian surface with rectangular sides and positive point charge +q at its
center. If all the dimensions of Gaussian surface double, but charge +q remains at its center,
the electric flux through the surface will
a) increase by a factor of 4
b) increase by a factor of 2
c) remain the same
d) decrease by a factor of 1/2
actual questions and CORRECT answers
Two charged balls are repelling each other as they hang from the ceiling. What can you say
about their charges?
a) one is positive, the other is negative
b) both are positive
c) both are negative
d) both are positive and negative - CORRECT ANSWER d) both are positive and
negative
When you rub a plastic rod with fur, the plastic rod becomes negatively charged and the fur
becomes positively charged. As a consequence of rubbing the rob with the fur,
a) the rod and fur both gain mass
b) the rod and fur both lose mass
c) the rod gains mass and the fur loses mass
d) the rod loses mass and the fur gains mass
e) none - CORRECT ANSWER c) the rod gains mass and the fur loses mass
What is the magnitude of the force F2?
a) 1.0 N
b) 1.5 N
c) 2.0 N
d) 3.0 N
e) 6.0 N - CORRECT ANSWER d) 3.0 N
If we increase one charge to 4Q, what is the magnitude of F1?
a) 3/4 N
, b) 3.0 N
c) 12 N
d) 16 N
3) 48 N - CORRECT ANSWER c) 12 N
Two balls with charges +Q and +4Q are fixed at a separation distance of 3R. Is it possible to
place another charged ball Q0 on the line between the two charges such that the net force on
Q0 will be zero?
a) yes, but only if Qo is positive
b) yes, but only if Qo is negative
c) yes, independent of the sign (or value) of Qo
d) no, the net force can never be zero - CORRECT ANSWER c) yes, independent of
the sign (or value) of Qo
When two point charges are a distance d apart, the electric force that each one feels from the
other has a magnitude F. In order to make this force twice as strong, the distance would have
to be changed to
a) 2d
b)square root 2 times d
c) d/square root 2
d) d/2
e) d/4 - CORRECT ANSWER c) d/square root 2
The figure shows a Gaussian surface with rectangular sides and positive point charge +q at its
center. If all the dimensions of Gaussian surface double, but charge +q remains at its center,
the electric flux through the surface will
a) increase by a factor of 4
b) increase by a factor of 2
c) remain the same
d) decrease by a factor of 1/2
