a wire has a resistance of 21 ohms . it is melted down to for a wire 3 times longer. what is the new resistance?
2007-03-20 17:51:16 · 3 answers · asked by Matthew C 1 in Science & Mathematics ➔ Engineering
the resistance is a function of the cross section area (reverse ratio), length of the wire (linear) and a constant.
if the new wire is 3 times longer then its cross section is 3 time smaller so the resistance is 9 times larger, I'll let you find the exact formula and calculate the result yourself ;-)
2007-03-20 18:52:31 · answer #1 · answered by eyal b 4 · 0⤊ 0⤋
189 ohms.
You have to reduce the cross sectional area by a factor of 3, if you want to increase the length by a factor of 3. This increases the resistance by a factor of 9. 9 x 21 = 189.
2007-03-21 10:36:32 · answer #2 · answered by joshnya68 4 · 0⤊ 0⤋
The resistance should triple. 63 ohms.
2007-03-21 01:45:42 · answer #3 · answered by Johnny 5 · 0⤊ 0⤋