EE $306$

$[$HOMEWORK #$6]$

A coil consists of $2000$ turns of copper wire having a cross$-$sectional area of $0\mathrm{.}8m{m}^2.$ The mean length per turn is $80$ cm and the resistivity of copper is $0\mathrm{.}02m$ at normal working temperature. Calculate the resistance of the coil and the power dissipated when the coil is connected across a $110$ V d$.$c$.$ supply.

The field winding of a d$.$c$.$ motor is connected directly across a $440$ V supply. When the winding is at the room temperature of $17C,$ the current is $2\mathrm{.}3$ A $.$ After the machine has been running for some hours, the current has fallen to $1\mathrm{.}9$ A $,$ the voltage remaining unaltered. Calculate the average temperature throughout the winding, assuming the temperature coefficient of resistance of copper to be $\frac{0\mathrm{.}00426}{}C$ at $0C.$

Estimate the resistance values of the following components:

$($a$)$

$($b$)$

$($c$)$

$($d$)$

$223$

$8202$

$4$R$7$

$($e$)$

$($f$)$

$($g$)$