Exam-style question
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Which of the following best describes the relationship between the oscillation period and the values of R_A, R_B, and C in an astable multivibrator?.
- A.Period is directly proportional to the sum of R_A and twice R_B and to C.
- B.Period is inversely proportional to the sum of R_A and twice R_B and to C.
- C.Period is directly proportional to the product of R_A, R_B, and C.
- D.Period is independent of R_A, R_B, and C.
Model answer
What a good answer should say
- Period is directly proportional to the sum of R_A and twice R_B and to C.
Explanation
Why this works
The standard formula for an astable 555 timer is T = 1.1 × (R_A + 2 R_B) × C, showing that the period scales linearly with the sum of R_A and twice R_B and with the capacitance C.
Common mistake
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