Undecided Question
At 40.1C, the resistance of a segment of gold wire is 129.6ohms?
At 40.1C, the resistance of a segment of gold
wire is 129.6
. When the wire is placed in a
liquid bath, the resistance decreases to 95.5
.
When the wire is placed in a liquid bath,the resistance decreases to 95.5 ohms
What is the temperature of the bath? The
temperature coefficient of resistivity for gold
is 0.0034 (C)−1 at 20C. Answer in C
Answer in units of C
its due 2/6/12 at midnight please help i got the answer to be -37.3C but it says im wrong?
wire is 129.6
. When the wire is placed in a
liquid bath, the resistance decreases to 95.5
.
When the wire is placed in a liquid bath,the resistance decreases to 95.5 ohms
What is the temperature of the bath? The
temperature coefficient of resistivity for gold
is 0.0034 (C)−1 at 20C. Answer in C
Answer in units of C
its due 2/6/12 at midnight please help i got the answer to be -37.3C but it says im wrong?
Answerer 0 2012-02-06 08:50:38 +0000
R(T) = R(20) * [1 + α(T - 20)]
=> R(40.1) = R(20) * [1 + α (40.1 - 20)]
=> 129.6 = R(20) * [1 + 20.1 α]
and 95.5 = R(20) * [1 + (T - 20) α]
Taking ratio,
(129.6) / (95.5) = (1 + 20.1 * 0.0034) / [1 + (0.0034) * (T - 20)]
=> 1 + (0.0034) (T - 20) = (1 + 20.1 * 0.0034) * (95.5)/(129.6)
=> (0.0034) T + 0.932 = 0.787
=> T = - (0.145) / (0.0034)
=> T = - 42.65° C.
[Note that you might have used the simplified approximate formula,
R(T2) = R(T1) * [1 + α (T2 - T1)].
Let me check if you really did it.
95.5 = 129.6 * [1 + (0.0034) (T2 - 40.1)]
=> (0.0034) (T2 - 40.1) = - 0.263
=> T2 - 40.1 = - 77.4
=> T2 = - 37.3° C.
This shows that you used the approximate formula and did not work oot using the formula going through resistance at 20° C.
R(T) = R(20) * [1 + α(T - 20)]
=> R(40.1) = R(20) * [1 + α (40.1 - 20)]
=> 129.6 = R(20) * [1 + 20.1 α]
and 95.5 = R(20) * [1 + (T - 20) α]
Taking ratio,
(129.6) / (95.5) = (1 + 20.1 * 0.0034) / [1 + (0.0034) * (T - 20)]
=> 1 + (0.0034) (T - 20) = (1 + 20.1 * 0.0034) * (95.5)/(129.6)
=> (0.0034) T + 0.932 = 0.787
=> T = - (0.145) / (0.0034)
=> T = - 42.65° C.
[Note that you might have used the simplified approximate formula,
R(T2) = R(T1) * [1 + α (T2 - T1)].
Let me check if you really did it.
95.5 = 129.6 * [1 + (0.0034) (T2 - 40.1)]
=> (0.0034) (T2 - 40.1) = - 0.263
=> T2 - 40.1 = - 77.4
=> T2 = - 37.3° C.
This shows that you used the approximate formula and did not work oot using the formula going through resistance at 20° C.
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