An electric heater draws a current of 20 A when connected to a 120 V power source. Its resistance is

Question

BlackTom AI · Accepted Answer

We start by identifying the key values given in the problem: a voltage source of 120 V and a current draw of 20 A. Using Ohm's law, the resistance is R = V / I.

Option 0.170 Ω: If the resistance were 0.170 Ω, the current would be I = V / R = 120 V / 0.170 Ω ≈ 705.88 A. This is far from the stated 20 A, so this option is inconsistent with the given data.

Option 6 Ω: If R = 6 Ω, then V = I × R = 20 A × 6 Ω = 120 V, which matches the supplied voltage. This alignment with both V and I confirms this option is internally consistent.

Option 8 Ω: With R = 8 Ω, the required voltage for 20 A would be V = I × R = 20 A × 8 Ω = 160 V. Since the source is only 120 V, this choice cannot be correct.

Option 2400 Ω: For R = 2400 Ω, the current at 120 V would be I = V / R = 120 V / 2400 Ω = 0.05 A, again not equal to the given 20 A. This option fails to satisfy the current condition.

In summary, each of the incorrect resistances leads to a voltage or current that disagrees with the provided values, while the 6 Ω option yields a self-consistent V = I × R relationship with the given 120 V and 20 A.

APPHYSC142-031 with labs Exam Review - Final

An electric heater draws a current of 20 A when connected to a 120 V power source. Its resistance is

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