How many ohms is the resistance of the lamp marked with pz220-100? If it is connected to a 110V circuit, how many watts is the actual power?

How many ohms is the resistance of the lamp marked with pz220-100? If it is connected to a 110V circuit, how many watts is the actual power?

According to P = u * U / R, r = u * U / P = 220 * 220 / 100 = 484 Ω
According to P = u * U / r = 110 * 110 / 484 = 25W

A lamp marked pz220-40 is connected to a 110V circuit. How many watts is its actual power?

P real: P amount = (U real: u amount) square
P real: 40 = (110:220) square
P real = 10W
That's all. Hope it works

What is the rated power of the lamp marked with 220 V, 60 W connected to 110 V voltage?

The rated power is 60W
The actual power is 15W

Is 0.3 megohm phase to ground resistance normal?

It's not normal
Because the minimum insulation resistance of all kinds of strong current installation specifications is 0.5 megohm, many of them are above 1.0 megohm
You are not qualified