Question

18. Water in an electric kettle connected to a
220 V supply takes 5 minutes to reach its boiling
point. How long will it take if the supply voltage
falls to 200 V ?​

Answer 1

Answer:

v....220v

t....5m= 300s

p=v square ×t /r of 1st 220v supply

p=v square × t / r of 2nd 200v supply

by equating both we get

t x 200 ^2/r = t x 220^2/300

t = 300x220/200

t=336 s

t = 6.05 minutes