Question

light from bathroom bulb gets dimmer for a moment when gieser is switched on. Why?

Answer 1

When a high volt taking machine(such as gieser,iron,heater,erc) turned on,the consumpsion of voltage gets high.As gieser consume more voltage electricity,thus,bulb gets dimmer.

Answer 2

Geyser draws large current initially from the supply which lowers voltage at bulb for a moment until it is stabilized by the transmission grid.