Question

i) A Potential difference of
200 Volt is applied to a coil at
a temperature of 15°c and the
current is 10 A • What will be
the temperature of the coil when the
current has fallen to 9A, the
applied voltage being the same
as before a temperature coeffcient
OF resistance cadet с –
234​

Answer 1

Question : A potential diffrence of 200 Volt is applied to a coil at a temperature of 15°C and the current is 10 Ampere. What will be the temperature of the coil when the current ha fallen to 9 Ampere, the applied voltage being the same as before ? And Temperature coffiecient of resistance (Alpha) = 1/234 /°C.

Solution : resistance of coil at temperature, T_i = 15°C , R₁ = 200/10 = 20 ohm.

Resistance of coil when current passing through coil is 9A, R₂ = 200/9 = 22.2 ohm

Now using formula, R = R₀[1 + α∆T]

Here, R₀ = R₁ = 20 ohm , R = R₂ = 22.2 ohm

So, 22.2 = 20[1 + 1/234 × (T - 15°C)]

⇒22.2 = 20 + 20/234 (T - 15)

⇒2.2 × 234/20 = T - 15

⇒25.74 = T - 15

⇒T = 40.74° C

Therefore the temperature of the coil will be 40.74°C.