(i) A potential difference of 200 volt is applied to a coil at a temperature of 15ºC and the current is 10 A. What will be the temperature of the coil when the current has fallen to 9 A, the applied voltage being the same as before? temperature coefficient of resistance ( α ) = 
ºC – 1 .
(ii) A platinum wire has resistance of 10 ohm at 0ºC and 20 ohm at 273 ºC. Find the value of temperature coefficient of resistance.
Text Solution
Verified by ExpertsCHECK THE SOLUTION.
[(i) 41ºC, (ii) 
ºC –1 .]
Sol. (i) R 15 = 
= 20 Ω , R t = 
Ω
R t = R 15 (1 + α 
t)
⇒ 
= 20 
= 
⇒ 
t = 
= 26 ⇒ t = 26 + 15 = 41º C.
(ii) α = 
⇒ α 
= 
α × 273 = λ n 
α = 
o C –1 .
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