Why result voltage gain with theory is different?

The difference between theoretical and actual voltage gain can arise from several factors, including non-ideal components, parasitic elements, and circuit loading effects. Real-world components often have tolerances and limitations that deviate from ideal characteristics, such as resistance, capacitance, and inductance. Additionally, the interaction between components can introduce unintended feedback or loss, impacting the overall gain. Environmental factors, such as temperature or frequency, can also influence performance, leading to discrepancies between theoretical predictions and practical results.