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AExE01 · Chapter 1Basic Electrical & Electronics🏛️ Past Licensure QuestionID: 2d34bc8d

The gain of an amplifier without feedback is 100 dB. If negative feedback of 3 dB is applied, the gain of the amplifier becomes:

Multiple Choice Options

A
5 dB
B
300 dB
C
97 dB
✓ Correct Option
D
103 dB

Detailed Technical Solution & Explanation

In logarithmic decibel units, applying negative feedback reduces amplifier gain by subtracting the feedback factor in decibels: $A_{f(\text{dB})} = A_{(\text{dB})} - N_{(\text{dB})} = 100\text{ dB} - 3\text{ dB} = 97\text{ dB}$ .

Option Analysis:

•

Option A (5 dB): Incorrect. Arbitrary incorrect subtraction.

•

Option B (300 dB): Incorrect. Decibels must not be multiplied.

•

Option C (97 dB): Correct. Negative feedback reduces the forward gain by 3 dB, resulting in

100 - 3 = 97\text{ dB}

•

Option D (103 dB): Incorrect. Adding 3 dB corresponds to positive feedback, not negative feedback.

Reference: Mock Test 03NEC Licensure Syllabus

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