Is there an internal resistivity in buzzers?
I would like to know if there is an internal resistance in buzzers


Without resistance (or at least the appearance of resistance) no power can be dissipated. If no power is dissipated then no sound can be emitted. Power relies on the conversion of electricity to some other form (such as sound or light).

So, if you have a buzzer that produces 90 dB SPL (sound pressure level) at 12 volts dc, that SPL is equivalent to "so many watts". It might be 10mW of acoustic power and that would look like a 10mW load to the 12V dc power supply. 10mW drawn from a 12V power supply is equivalent to a resistor across 12V of 14.4 k ohm and a current of 0.8333 mA

The trouble is in this scenario is that conversion efficiency is going to be about 10% and this means that the power taken (to produce a real sound power of 10 mW) is going to be about 100mW and so, the buzzer is going to look like a resistance of maybe 1440 ohms.