Exam 2 Flashcards
A membrane is permeable to positive ions. Unequal concentrations of positive ions on either side of the membrane result in a flow of positive charge from high concentration to low concentration. Which side of the membrane is at a higher electric potential after equilibrium is reached?
A. The high concentration side
B. The low concentration side
E. Neither - the two sides have equal potential
E. Neither - the two sides have equal potential
The screening (Debye) length of a charge in a salt solution
i. Increases as the concentration of salt ions increases
ii. Increases as the temperature increases
iii. Decreases as the charge of the salt ions increases
A. i. and ii.
B. ii. and iii.
C. i. and iii.
D. i., ii., and iii.
B. ii and iii
The screening (Debye) length of a charge in a salt solution
ii. increases as the temperature increases
iii. Decreases as the charge of the salt ions increases
The potential difference across a membrane does not depend on which of the following quantities:
A. Temperature
B. The electric charge of ions passing through the membrane
C. The concentrations of ions on either side of the membrane
D. The thickness of the membrane
D. The thickness of the membrane
What does adding dielectric materials do to the capacitance of a capacitor?
Increases capacitance
The membrane allows both positive and negative ions to pass through. What will the concentrations look like after a long time has passed?
A. The concentrations would look the same as at the beginning
B. The concentrations on the left and right sides would look reversed from what they were at the beginning
C. The concentration of positive ions will be higher on one side, and the concentration of the negative ions will be higher on the other side
D. All concentrations - positive and negative, left side and right side - would be equal
D. All concentrations - positive and negative, left side and right side - would be equal
The membrane allows only positive ions to pass through. How will the concentrations change as time passes?
A. The negative ion concentrations would stay the same, but the positive ion concentration would decrease on the left and increase on the right
B. Both the negative and the positive ion concentrations would stay the same
C. Both negative and the positive ion concentrations would decrease on the left and increase on the right
A. The negative ion concentrations would stay the same, but the positive ion concentration would decrease on the left and increase on the right
The membrane allows only positive ions to pass through. What will be the net charge on either side of the membrane after some time has passed?
A. Both side will still have zero net charge
B. The left side will have a net negative charge and the right side will have a net positive charge
C. The left side will have a net positive charge and the right side will have a net negative charge
B. The left side will have a net negative charge and the right side will have a net positive charge
The membrane allows only positive ions to pass through. Which side of the membrane will have a higher electric potential after some time has passed?
A. The left side (high concentration)
B. The right side (low concentration)
C. There’s no way to tell
B. The right side (low concentration)
Which side of the membrane would be at a higher electric potential if the membrane allowed only negative ions to pass through?
A. The left side (high concentration)
B. The right side (low concentration)
A. The left side (high concentration)
Which of the following would correspond to a greater current?
A. A smaller amount of charge passing through a conductor over a larger time interval
B. A decrease in the density of moving chargers per unit volume
C. An increase in the speed of the moving charges
D. A decrease in the cross section area of the conductor
C. An increase in the speed of the moving charges
A cylinder has a fixed resistance. What happens to the electric current in the cylinder if the potential difference between the ends of the cylinder is doubled?
A. The current is doubled
B. The current is halved
C. The current is unchanged
D. None of the above
A. The current is doubled
The signs of the currents for positive charges flowing to the left and negative charges flowing to the right are
A. The same
B. Opposite
C. It depends on which direction we choose to be positive
A. The same
