The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. Find the number of electrons striking the target per second.

Four resistors of 5 Ω, 15 Ω, 20 Ω and 40 Ω are connected in series. The equivalent resistance of the combination is ______.

A 100 W bulb is connected to a 220 V supply. The current through the bulb is approximately:

A light bulb is rated at 200 W for a 130 V supply. Find the resistance of the bulb.