What is the basis of the ability of a transistor to amplify electrical signals?

When the emitter pn junction is turned on in the forward direction, the emitter injects into the base a large number of minority carriers – holes. As a result, the resistance of the emitter junction turns out to be small. Therefore, with a small change in the base raised, due to a change in the amplified signal U, the current I of the emitter will change greatly due to the small resistance of the emitter junction.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.