17. NCERT Exemplar VIII

 

Initially, the bulb did not glow because the solution's concentrationvoltagesolution's volumecurrent required to make the bulb glow was insufficient. With the addition of another cell, the solution's concentrationcurrentvoltagesolution's volume rises, indicating that the current flowing through the bulb reaches a certain level, and the bulb starts to shine as it receives enough energy to temperaturecurrentvoltageheat its filament.