A glass rod acquires charge by rubbing silk cloth. The charge on the glass is due to: (a) Friction
(b) Conduction
(c) Induction
(d) Radiation

Explanation:

glass rod acquires charge by rubbing with silk cloth the charge on the glass is due to friction...

(a)Friction

Explanation:

It is due to friction as you are rubbing the glass rod with silk cloth  

as friction occurs when 2 surfaces are rubbed against each other

Therefore it is charging by friction

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