Question

in what condition a bulb in a circuit not glow​

Answer 1

The tungsten wire melt

When the bulb becomes fuse, then its tungsten wire melt. As a result, the circuit become open. Thus, electric supply to the bulb stops. Further, in fused condition the part which is responsible for glowing of bulb(tungsten) becomes damage. Hence, the bulb does not glow.

Answer 2

Answer:

if connection is loose

if bulb is fuse

if wires are not connected properly