use this,
since α=(1/R)(dR/dt)
1/R= 1/R1+1/R2 ,
differentiate both sides....
1/R2(dR/dt)=1/R12(dR1/dt) +1/R22(dR2/dt)
;
A resistor of resistance R and temp. coeff. of resistivity=α is connected in parallel with a resistor of resistance 3R and temp. coeff. of resistivity=2α.Find equivalent α.
use this,
since α=(1/R)(dR/dt)
1/R= 1/R1+1/R2 ,
differentiate both sides....
1/R2(dR/dt)=1/R12(dR1/dt) +1/R22(dR2/dt)
;