Question

two electric lamps A and B are marked 220v-100w and 220v-60w.out of the two which lamp has higher resistance?

Answer 1

FOR LAMP A - P = 100 w , v = 220

By P= V^2 / R

R = V^2 / P
NOW BY PUTTING VALUES

R = 220 X 220 / 100
R = 48400 / 100
R = 484 OHMS

For lamp B - P=60w , v=220

By P= V^2 / R

R = V^2 / P
NOW BY PUTTING VALUES

R = 220 X 220 / 60
R = 48400 / 60
R = 806.67 OHMS

HENCE , RESISTANCE OF LAMP 'B' WILL BE MORE IF COMPARED TO LAMP 'A'.