You have a fine wire with a cross sectional area of 9.4×10−10 m2
View Single Post
Mar17-12, 09:54 PM
You have a fine wire
with a cross sectional area of 9.4×10−10 m2
and a length of 1.1 m. You wish to determine what it is made out of, so you connect it to a standard AA battery (1.5 V) and measure a current of 0.048 A. What material is the wire most likely made out of?
The options for the resistivities are as follows:
Iron (but iron is wrong, so discard)
I found the resistance by multiplying the current (.048 A) and voltage (1.5). I got .072 ohms.
I'm sort of confused about the area though
. Would it be A=∏(9.4×10−10)
, or what?
Then when I solve I get .072=ρ(1.1/2.95E-9)
ρ= 1.9E-10 ohm meters.
I only have one shot of getting the answer. I'm confused, do it right, and in that case is it closest to aluminum or silver? My friend had aluminum, and we might have the same numbers. PLEASE HELP!
Read those two bits in red and see if you are still confused.