The Bell, known in Sanskrit as the Ghanta/Ghanti is used in all poojas for invoking the Gods. The ringing of the bell produces what is regarded as an auspicious sound.
It produces the sound Om, the universal name of the Lord. The fine combination of pure brass and bronze produces a harmonious and rich tonal sound the sound of the bell and the sound of the Vedas also radiate Omkaara naadh.
The sound of the bell evacuates negative energy, to help drive out negative energy / evil spirit from the place of worship. Bells are believed to frighten away evil spirits or used to cast or remove spells.