Question

Sometimes an electric bulb does not glow even if it is connected to a cell . What could be the reason ?

Answer 1

Electric bulb need sufficient voltage to glow .If it does not have sufficient voltage , then it does not glow.

Answer 2

The cell  is having low voltage and used  for LED's to glow which requires less voltage.Hence electric buld doesn't glow when it is connected to cell,because it requies high voltage.