What is the minimum resistance of a 50k Potentiometer used as a rheostat?

Question

Is it 1 Ohm or just really zero Ohm? or maybe 0.1 Ohm? or 10 Ohm? 100 Ohm?

Answer 1

It should go to a nominal zero, well less than 1 ohm.

Nothing is "really zero ohms". A copper bar 1" in diameter that can handle 1000 amps does not have zero ohms.

What is much higher is if you move the slider slightly away from the end, the resistance will jump to probably a value of hundreds of ohms.

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Answer 2

Most pots consist of a wiper that travels along a resistive film or wire. At each end, the film/wire is connected to a terminal. The wiper can usually contact the terminal, so resistance should go to zero. In real life, you rarely see any resistance that is truly zero, but should go well under 1 Ohm, say  milliOhm range or smaller. Sometimes there is a design feature that does cause some resistance, if this is critical get a sample and measure the resistance to be sure.