The Working of an atomizer depends upon

The correct option is Bernoulli's theorem.

Detailed Explanation:

An atomizer (often used in perfume sprays, paint sprayers, and carburetors) is a device used to produce a fine mist of liquid droplets. The operation of an atomizer is a direct application of Bernoulli's theorem in fluid dynamics.

According to Bernoulli's theorem, for the steady flow of an ideal fluid, the sum of pressure energy, kinetic energy, and potential energy per unit volume is constant along any streamline. Neglecting changes in height, the relation can be expressed as:

$P+\frac{1}{2}\rho v^2=\text{constant}$

Where:
- $P$ is the static pressure of the fluid,
- $\rho$ is the density of the fluid, and
- $v$ is the velocity of the fluid flow.

This principle implies that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure.

Step-by-Step Working of an Atomizer:
1. When the squeeze bulb of the atomizer is pressed, air is forced to flow rapidly through a horizontal tube.
2. As the air velocity ($v$) increases inside the horizontal tube, the pressure ($P$) in that high-speed air region drops significantly below the normal atmospheric pressure, creating a localized low-pressure zone.
3. A vertical tube is dipped into the liquid container at one end, while its upper end opens into this horizontal low-pressure zone.
4. The liquid surface in the container is exposed to normal atmospheric pressure, which is higher than the low pressure at the top of the vertical tube. This pressure difference forces the liquid to rise up the vertical tube.
5. Upon reaching the top of the tube, the liquid is blown into tiny droplets by the high-speed stream of air, forming a fine spray or mist.