Working of Vibrating Reed Frequency Meter

Working of Vibrating Reed Frequency Meter Points : Working of Vibrating Reed Frequency Meter When the electromagnet is connected across the supply whose frequency is to be measured, its magnetism alternates with the same frequency. Hence the electromagnet exerts attraction force on each reed once every half cycle. All reeds tend to vibrate but only that whose natural frequency is exactly double the supply frequency vibrates with maximum amplitude due to mechanical resonance.

The supply frequency is reed directly by noting the scale mark opposite the white painted flag which is vibrating he most (f=50Hz). The vibrations of other reeds would be so small as to be almost unobservable. For a frequency exactly midway between the natural frequencies of the two reeds (fi=49.75Hz), both will vibrate with amplitudes which are equal but much less than when the supply frequency exactly consider with that of one of the reeds. Range Such instruments have a small range usually from 47 to 53 Hz or from 57 to 63 Hz etc. The frequency range of a given set of reeds may be doubled by polarizing the electromagnet.