Question

Question #b95b1

Answer 1

Let the resistance of the original coil of electromanet be `ROmega`

For given V = 122V and I =12A

`R=V/I=122/14`

(a) Let `r_1 Omega` be the resistance to be connected in series to limit the current to the rated value of 12A.

So `122/(R+r_1)=12`

`=>r_1=122/12-R=122/12-122/14=(122xx2)/(12xx14)`

`=1.45Omega`

(b) Let `r_2 Omega` be the resistance to be connected in series to limit the current to the of 9A.

So `122/(R+r_2)=9`

`=>r_2=122/9-R=122/9-122/14=(122xx5)/(9xx14)`

`=4.84Omega`