Question

Q1.Two wires of resistance R1 and R2 have temperature coefficient of resistance Alpha 1 in Alpha 2 respectively, these are joined in series. The effective temperature coefficient of resistance is: ----

Answer 1

Answer:

{(R1α1 + R2α2)/(R1 + R2)}

Step-by-step explanation:

Suppose at t°c, resistance of two wires become R1t & R2t & their  equivalent is Rt.

Hence Rt = R1t + R2t

Also  R1t = R1(1 + α1t) R2t = R2(1 + α2t)

∴ Rt = R1(1 + α1t) + R2(1 + α2t)

= R1 + R2 + (R1α­1 + R2α2)t

= (R1 + R2) [1 + {(R1α1 + R2α2)/(R1 + R2)}t]

∴ Effective temp coefficient is

{(R1α1 + R2α2)/(R1 + R2)}

Hope It helps you.

Answer 2

The thermal coefficient of resistance is ⇒

α= 1/R dt/dR

Equivalent resistance in series= R1 +R2 =Req.

Rest is above.