In a circuit containing two unequal resistors connected in parallel:

n equal resistors are first connected in series and then connected in parallel. The ratio of the maximum to the minimum resistance is:

If R₁ and R₂ are the resistances of filaments of a 400 W and a 200 W lamp, designed to operate on the same voltage, then:

The equivalent resistance in series combination is:

A house is fitted with 5 tubes each f 40 W. If all the tubes are lighted for 20 hours and if the cost of electrical unit is Rs. 0.50, the total cost of electricity consumed is: