Question

only genious can solve it ,please solve it urgent.

Answer 1

Specific heat of water = 4.2 J/gm/°C.

Heat energy required to heat 40 kg from 15°C to 80°C = H.

H = m s T = 40, 000* 4.2* (80-15) J
= 260, 000 ×4.2 J
Power dissipated by the resistor = P = V^2/R
= 220 × 220/12 W
= 12, 100/3 W

Time t in sec. = t = H/P

Use calculator to get the answer.