Question

Two resistors of 60 ohms and 40 ohms are arranged in series across a 220 volt supply. How much heat is produced by this combination in half a minute?

• A. 12860J
• B. 152698J
• C. 650J
• D. 14520J

Answer 1

The correct option is D 14520J

Answer is D.
Components connected in series are connected along a single path, so the same current flows through all of the components. The current through each of the components is the same, and the voltage across the circuit is the sum of the voltages across each component. The total resistance of resistors in series is equal to the sum of their individual resistances. That is, $R_{total}=R_1+R_2...R_n$.
In this case, the total resistance is 60+40 = 100 ohms and the total voltage is 220 V.
Energy ($power\times time$) is measured in Joules and by including time (t) in the power formulae, the energy dissipated by a component or circuit can be calculated.
Energy dissipated = Pt or $VI\times tasP=VI$.
It can also be written as $P=\frac{V^2}{R}\times tasI=\frac{V}{R}$.
Here, V = 220 V, R = 100 ohms and t = half minute = 30 seconds.
Therefore, $P=\frac{{220}^2}{100}\times 30=14520J$.
Hence, the heat produced by this combination in half a minute is 14520 J.