Question

 Four heater, each having a resistance of 30Ω, are connected in series across a 600v train circuit. 

Find the current?

Answer 1

Gives

$$R_1=R_2=R_3=R_4=R=30\Omega$$

V=600volt

$$R_{net}=R_1+R_2+R_3+R_4\\R_{net}=30+30+30+30=120\Omega$$

Current

$I=\frac{v}{R_{net}}=\frac{300}{120}=2.5Amp$