PHY 202 Exam 2 UPDATED QUESTIONS AND CORRECT ANSWERS

PHY 202 Exam 2 UPDATED QUESTIONS
AND CORRECT ANSWERS
When electric current is flowing in a

metal, the electrons are moving

A. at nearly the speed of light.

B. at the speed of light.

C. at the speed of sound in the metal.

D. at the speed of sound in air.

E. at none of the above speeds. - CORRECT ANSWER none of speeds



A cylindrical wire has a resistance R and

resistivity ρ. If its length and diameter are

BOTH cut in half, what will be its

resistance?

A. 4R

B. 2R

C. R

D. R/2

E. R/4 - CORRECT ANSWER b



A cylindrical wire has a resistance R

and resistivity ρ. If its length and diameter

are BOTH cut in half, what will be its

resistivity?

A. 4p

B.2p

C. p

D. p/2

E. p/4 - CORRECT ANSWER c

, A wire of resistivity ρ must be replaced

in a circuit by a wire of the same material

but 4 times as long. If, however, the

resistance of the new wire is to be the same

as the resistance of the original wire, the

diameter of the new wire must be

A. the same

B. 1/2 times

C. 1/4 times

D. 2 times

E. 4 times - CORRECT ANSWER d



As current flows through a uniform

wire, the wire gets hotter because the

electrons stop moving and therefore

transform their lost kinetic energy into

thermal energy in the wire.

A. True

B. False - CORRECT ANSWER b



Two cables of the same length are

made of the same material, except that one

cable has twice the diameter of the other

cable. When the same potential difference

is maintained across both cables, which of

the following statements are true? (There

may be more than one correct choice.)

A. The same current flows through both

cables.

B. Both cables carry the same current