CH 26 and CH 27 Phys 232 Exam 2026
Questions and Answers
Which way does current flow? - Correct answer-CUrrent flows from higher to
lower electric potential
If the resistance of a copper wire is R, what is the resistance of another copper wire
that is twice as ling and has twice the diameter of the first wire? - Correct answer-
Less than R
Length increases by 2x
Area increases by 4x
R= (row)L/A
Two wires, A and B, are made of the same metal and have equal length, but the
resistance of wire A is four times the resistance of wire B. How do their diameters
compare? - Correct answer-The resistance of wire A is greater because its area is
less than wire B. Since area is related to radius (or diameter) squared, the diameter
of A must be two times less than B. R=(row)L/A -> dA= 1/2 dB
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, Two copper wires of different diameter are joined end to end, and a current flows
in the wire combination. When electrons move from the larger-diameter wire into
the smaller-diameter wire, what happens to their drift speed and current?
I=dQ/dt=nqvA - Correct answer-Their drift speed increases
Electrons in an electric circuit pass through a resistor. The wire has the same
diameter on each side of the resistor. Compared to the drift speed of the electrons
before entering the resistor, the drift speed of the electrons after leaving the resistor
is - Correct answer-The Same
The drift current speeds up in the smaller diameter wire, but then slows when it
returns to a larger diameter wire.
Why do light bulbs often burn out right when you turn them on? - Correct answer-
There is a surge in current when the light is turned on
As temperature goes up, R increases so the current (I) decreases. It may melt
before the current decreases.
Electrons in an electric circuit pass through a resistor. The wire has the same
diameter on each side of the resistor. Compared to the potential energy of an
electron before entering the resistor, the potential energy of an electron after
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Questions and Answers
Which way does current flow? - Correct answer-CUrrent flows from higher to
lower electric potential
If the resistance of a copper wire is R, what is the resistance of another copper wire
that is twice as ling and has twice the diameter of the first wire? - Correct answer-
Less than R
Length increases by 2x
Area increases by 4x
R= (row)L/A
Two wires, A and B, are made of the same metal and have equal length, but the
resistance of wire A is four times the resistance of wire B. How do their diameters
compare? - Correct answer-The resistance of wire A is greater because its area is
less than wire B. Since area is related to radius (or diameter) squared, the diameter
of A must be two times less than B. R=(row)L/A -> dA= 1/2 dB
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
, Two copper wires of different diameter are joined end to end, and a current flows
in the wire combination. When electrons move from the larger-diameter wire into
the smaller-diameter wire, what happens to their drift speed and current?
I=dQ/dt=nqvA - Correct answer-Their drift speed increases
Electrons in an electric circuit pass through a resistor. The wire has the same
diameter on each side of the resistor. Compared to the drift speed of the electrons
before entering the resistor, the drift speed of the electrons after leaving the resistor
is - Correct answer-The Same
The drift current speeds up in the smaller diameter wire, but then slows when it
returns to a larger diameter wire.
Why do light bulbs often burn out right when you turn them on? - Correct answer-
There is a surge in current when the light is turned on
As temperature goes up, R increases so the current (I) decreases. It may melt
before the current decreases.
Electrons in an electric circuit pass through a resistor. The wire has the same
diameter on each side of the resistor. Compared to the potential energy of an
electron before entering the resistor, the potential energy of an electron after
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
