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Question
In a CE transistor amplifier there is a current and voltage gain associated with the circuit. In other words there is a power gain. Considering power a measure of energy, does the circuit voilate conservation of energy?
Solution
The different gains in CE transistor amplifier:
- Ac current gain `beta_(ac) = ((Δi_c)/(Δi_b)) V_(CE)` = constant
- DC current gain: `beta_(dc) = i_c/i_b`
- Voltage gain: `A_y = (ΔV_o)/(ΔV_i) = beta_(ac) xx "Resistance gain"`
- Power gain: = `(ΔP_o)/(ΔP_i) = beta_(ac)^2 xx "Resistance gain"`
The power gain is very high in the CE transistor amplifier. In this circuit, the extra power required for amplified output is obtained from a DC source. Thus, the circuit used does not violate the law of conservation.
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