Questions 10 – 13 refer to a portion of a 15 centimeter length of wire which is

given resistance R = 1250 length = L = 0.15 m area of cross sewction A = 1.4*10^-10 m^2 10) c) There is not enough information given to know!!

ID: 1402554 • Letter: Q

Question

Questions 10 – 13 refer to a portion of a 15 centimeter length of wire which is connected to a voltage source.

The potential at each end is marked.

10. What is the direction of the current, I , in this portion of wire? (1)

a) to the right b) to the left c) There is not enough information given to know!!

11. If the cross-sectional area of the wire is 1.4 x10-10 m2, what is the resistivity of the metal that composes the wire?

Answer: ___________________ m (1)

12. How would the resistance of the wire change if it were stretched to become longer and thinner? (1)

a) The resistance would increase. b) The resistance would decrease. c) The resistance would remain the same.

13. What effect would the change in previous question have on the current in the wire? (1)

a) The current would increase. b) The current would decrease. c) The current would remain the same.

given resistance R = 1250

length = L = 0.15 m

area of cross sewction A = 1.4*10^-10 m^2

10)

c) There is not enough information given to know!! <<-------answer

11)

resistivity rho = R*A/L

rho = (1250*1.4*10^-10)/0.15 = 1.167*10^-6 ohm m <<-------answer

12)

volume = A*L

resistance R = rho*L/A

R = rho*L*L/A*L

R = rho*L^2/V

if the wire is stretched the volume remains same

R is proportional to L^2

as the length increases the resistance increases <<-----answer

13)

from ohms law

i = dV/R

as Resistance increases the current i decreases

b) The current would decrease <<-----answer

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