A number of parallel connected 110 V lamps are fed a 130 V battery having an internal resistance of

Question

A number of parallel connected 110 V lamps are fed a 130 V battery having an internal resistance of 2.6 ohm . If the resistance of each lamp is 200 ohm and the resistance of conducting wires is 0.40 ohm, the number of lamps which the battery can supply is\

Professor PC Thomas Classes · Answer

$V=\frac{E R}{R+r}$\ $\mathrm{E}=130 \mathrm{~V} \quad \mathrm{~V}=110 \mathrm{~V}$\ Let there be n bulbs. Then\ $\mathrm{R}=\frac{200}{\mathrm{n}} \Omega$\ $\mathrm{r}=2.6+0.4=3 \Omega$ $$ 110=\frac{130 	imes\left(\frac{200}{n}ight)}{\frac{200}{n}+3} $$ Solve.\