Resistance of a wire at 20°C is 20 Ω and at 500°C is60Ω . At what

1.	Resistance of a wire at 20°C is 20 Ω and at 500°C is60Ω . At what temperature its resistance is 25 Ω
Answer» If α is the temperature coefficient of resistance, R' is the initial resistance at initial temperature, then we know that: R=R'(1+α ΔT) where ΔT= Final temperature- initial temperature Change in temperature is (500-20) =480 degrees Initial Resistance= 20 ohm Final resistance =60 ohm Thus, 60=20(1+(α.480)) From this, α=0.004166 /C =0.4166 X 10^(-2) /C Now: The temperature at which its resistance is 25 ohm: R=R'(1+α ΔT) 25=20(1+ (0.004166)(T-20)) Thus, T= 80 degrees

Resistance of a wire at 20°C is 20 Ω and at 500°C is60Ω . At what temperature its resistance is 25 Ω

Answer»

If α is the temperature coefficient of resistance, R' is the initial resistance at initial temperature, then we know that:

R=R'(1+α ΔT)

where ΔT= Final temperature- initial temperature

Change in temperature is (500-20) =480 degrees

Initial Resistance= 20 ohm

Final resistance =60 ohm

Thus,

60=20(1+(α.480))

From this,

α=0.004166 /C =0.4166 X 10^(-2) /C

Now: The temperature at which its resistance is 25 ohm:

R=R'(1+α ΔT)

25=20(1+ (0.004166)(T-20))

Thus, T= 80 degrees

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Resistance of a wire at 20°C is 20 Ω and at 500°C is60Ω . At what temperature its resistance is 25 Ω

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