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A 120 V lamp-dimming circuit is controlled by a rheostat and protected from excessive current by a 3 A fuse. To what minimum resistance value can the rheostat be set without blowing the fuse? Assume a lamp resistance of 20 ohms.

40 Ω
4 Ω
2 Ω
20 Ω

Correct Answer: 20 Ω

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