What happens to the pressure in a compressor as air passes through each stage?

In a compressor, as air passes through each stage, the pressure increases. This increase in pressure occurs because compressors are designed to reduce the volume of the air while simultaneously increasing its pressure. Each stage of the compressor applies work to the air, compressing it further, which is in accordance with the principles of thermodynamics where a reduction in volume typically leads to an increase in pressure.

In multistage compressors, this process is repeated through different compression stages, allowing for higher pressures to be achieved effectively. The design enables the compressor to attain desired pressure levels without causing excessive temperature increases, which are managed by intercooling between stages.

The other options do not accurately describe the behavior of pressure in a compressor. As mentioned, the pressure cannot decrease or remain constant in a functioning compressor, nor does it simply fluctuate; it follows a consistent pattern of increasing pressure throughout the compression process.