When the voltage at both ends of a resistor is 6, its resistance is 20 ohm. When the voltage at both ends of the resistor becomes 0 V, how many ohm is its resistance? When it becomes a superconductor at ultra-low temperature, how many ohm is its resistance

When the voltage at both ends of a resistor is 6, its resistance is 20 ohm. When the voltage at both ends of the resistor becomes 0 V, how many ohm is its resistance? When it becomes a superconductor at ultra-low temperature, how many ohm is its resistance

Without voltage, the resistance is still 20 ohm; if it becomes a superconductor, the resistance is zero

A "pz220-100" bulb with a rated voltage of______ v. Rated power is______ w. What is the resistance of the filament______ Ω．

The meaning of pz220-100 is: ordinary bulb, voltage is 220V, power is 100W, from P = u2r: r = u2p = 484 Ω. So the answer is: 220100484

In the experiment of measuring the resistance and rated power of the small bulb, it is known that the rated voltage of the small bulb is 3.8V, the filament resistance is greater than 10 ohm under normal illumination, and the power supply voltage is
6V, existing sliding rheostat (10 ohm, 1a and 5 ohm, 0.5A)
Ask which sliding rheostat you should choose and explain why

3.8:（6-3.8)=10:R
3.8:2.2=10:R
3.8R=22R
R = 5.79 ohm > 5, choose 10 ohm, 1A sliding rheostat