mm wrote:

Which uses more electricity, a 75 watt light bulb, or a 150 with a
dimmer so that it is only as bright as the 75?

If one uses more, does it use much more?

The 150 on the dimmer. Light bulb efficiency drops off *a lot* the
more you reduce the voltage. As the filament temperature drops, the
bulb puts out a little less heat, but a lot less light.

For a 150W bulb to put out the same amount of light as a 75W bulb
would require about 100W of electrical power.