Question:medium

A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

Updated On: Jan 13, 2026
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Solution and Explanation

Supply voltage: \(V= 220 \ V\)
Resistance of a single coil: \(R= 24\ Ω\)
Scenario (i): Individual coil usage
Using Ohm's law: \(V= I_1R_1\)
Where \(I_1\) is the current through the coil.
\(I_1 = \frac {V}{R_1}\) is calculated as \(\frac {220}{24}\), resulting in \(I_1= 9.166 \ A\).
Thus, 9.16 A flows through the coil when used individually.

Scenario (ii): Coils in series
Total resistance: \(R_2 = 24 Ω + 24 Ω = 48 Ω\)
From Ohm's law: \(V = I_2R_2\)
Where \(I_2\) is the current in the series circuit.
\(I_2 = \frac {V}{R_2}\) is calculated as \(\frac {220}{48}\), resulting in \(I_2 = 4.58\  A\).
Therefore, 4.58 A flows through the circuit when coils are connected in series.

Scenario (iii): Coils in parallel
Total resistance: \(R_3\) = \(\frac {1}{\frac {1}{24}+\frac {1}{24}}\) = \(\frac {24}{2}\) = \(12\  Ω\)
According to Ohm's law: \(V= I_3R_3\)
Where \(I_3\) is the current flowing through the circuit.
\(I_3 = \frac {V}{R_3}\) is calculated as \(\frac {220}{12}\), resulting in \(I_3= 18.33\  A\).
Hence, 18.33 A flows through the circuit when coils are connected in parallel.

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