An electric dimmer swich for light could reduce the light output by?

Answer 1

100%

Answer 2

An electric dimmer switch is like a variable resistor. When reducing the amount of light it just means that the current has to travel through more wires, meaning it can drop less energy to the bulb.
But a dimmer switch cannot completely reduce the light by 100%(meaning the lamp will not emit light). This only occurs when the circuit is broken.
So a dimmer switch will only reduce the light to about 95%

Answer 3

As others have already stated - Resistance; however, we need to remember we do not live in a perfect wrold. So a conductor is not a perfect conductor and that is the reason there is resistanc present even in the best conductor. So our resistor is not perfect either, even at its 100% position it will still permit some current to flow. But it usually is not enough to do the job intended, in this case light the bulb.
This would also apply to the exact opposite situation, the 0% resistance is not going to be perfect either, there will be some resistance present, even when there should be none.
If I were to guess, I have to say at 0% there is probably less than 2% resistance present, and at 100% at least the 95% present, probably closer to 97%.but neither will be perfect.

Answer 4

Well a dimmer swtich usually puts a variable resistance in the curcuit. It could cut the light output by anything between 0 and 100%

Answer 5

A modern triac (dimmer switch as opposed to a rheostat or saturable reactor) can cut the light output to 0-95% of full on.
Full on of a triac is only 95% (some may have special shorting switches to give 100%)
The triac works by either being full conducting or fully non-conducting (instantly)
It only works with AC because it uses a little bit of voltage (through a variable resistor) to trigger its conducting state twice every cycle. i.e., the resistor sets the point in the half-cycle where the triac becomes conductive. The triac resets to non-conductive at the next polarity transition.