Question

how can you charge an object such as a metal cylinder by conduction

Answer 1

Charging by conductioninvolves the contact of a charged object with a neutral object. Theobjects like metal cylinder can becharged by bringing a charged objectlike charged aluminium plate in contact with it. The metal cylinderacquires the same charge as that of aluminium plate.
$\leqslant answer \: by \: \\ \: \: \: \: \: \: \: \: akshat \: rajput \geqslant ....$

Answer 2

By making a contact between the metal cylinder and any charged object.