The resistance of an alloy wire is 25ohm when it is placed in a cup of melting ice.At room temperature of 28度,the resistance is 38ohm.If the wire is put in boiling water,what will be the resistance?
Please explain and calculate.
Thx
The ans is 71 ohm
2006-10-28 09:13:39 · 2 個解答 · 發問者 2003 2 in 科學 ➔ 其他：科學
It is very easy to see that when the temperature increase 28C, the esistance increase 13ohm, so that for increase 1C, the resistance will increase 0.46ohm (By 13/28), that means when the temperature increase 100C, the resistance will increase 46ohm
So, the require answer is:
46ohm + 25ohm = 71ohm
2006-10-28 15:09:45 補充：
sorry...there is a typing mistake, just let esistance be resistance, ok?
2006-10-28 15:11:10 補充：
Note that resistance increase linearly with temperature.
2006-10-28 11:07:49 · answer #1 · answered by ? 6 · 0⤊ 0⤋
There is another way of doing the calculation and I think is more precise.
The realtion is R = Ro(1+phita X T)
where R is the resistance at a certain temperature.
Ro is the resistance at a particular temperature. say 0 oC
phita is an greek symbol looks like 0.
T is the temperature difference.
with 38 = 25(1+phita X 28)
phita = 0.018571428
R = 25(1+0.018571428X100)
R = 71.4286 ohm
2006-10-28 11:43:13 · answer #2 · answered by ? 7 · 0⤊ 0⤋