Problem

Two heaters designed for the same voltage

V

have different power ratings. When connected individually across a source of voltage

V

, they produce

H

amount of heat each in time

t_1

and

t_2

respectively. When used together across the same source, they produce

H

amount of heat in time

t

(a) If they are in series,

t = t_1 + t_2

(b) If they are in series,

t = 2(t_1 + t_2)

t = \frac{t_1 t_2}{(t_1 + t_2)}

(d) If they are in parallel,

t = \frac{t_1 t_2}{2(t_1 + t_2)}