Given Vout = 500 mV and Vin = 1.3 V, compute the voltage ratio Vout/Vin in decibels (dB)__________?
Show answer Hide answer
Answer: C. -8.30 dB
Explanation
Voltage ratio in decibels is calculated as twenty times the common logarithm of output over input voltage. Dividing zero point five volts by one point three volts yields approximately zero point three eight four six. Taking the log and multiplying by twenty gives negative eight point thirty decibels of attenuation. The decibel is a logarithmic unit used to express the ratio of two electrical power or voltage levels. A negative decibel value indicates that the output signal voltage is smaller than the input voltage. Logarithmic scales simplify the calculation of cascaded amplifier gains and filter attenuations.
Audio and radio frequency engineers use decibels daily to measure amplifier attenuation and signal loss. Voltage attenuators are designed to reduce signal amplitudes accurately in electronic measurement instruments. Signal integrity analysis relies on decibel measurements to evaluate filter performance across frequencies. Option A suggests zero decibels, which would mean the output and input voltages are identical. Option B suggests positive eight point thirty decibels, ignoring the signal loss attenuation. Option D suggests zero point eight decibels, which results from an incorrect mathematical calculation.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Long-distance transmission lines are appropriately protected using which of the following relay types?
Show answer Hide answer
Answer: B. Mho’s relay
Mho relays provide directional distance protection that naturally accommodates the impedance characteristics of long transmission lines. Operating characteristics of mho relays remain stable and reliable under heavy powe...
Q2. What parameters are defined as the fundamental constants of transmission lines ?
Show answer Hide answer
Answer: D. All of the above
Resistance, inductance, and capacitance are distributed uniformly along transmission lines. These parameters determine the fundamental electrical characteristics and wave propagation properties. Engineers model power lin...
Q3. Calculate the primary-to-secondary transformer turns ratio (Np/Ns) required to match an 8000 O transistor output impedance to a 4 O speaker ?
Show answer Hide answer
Answer: B. 7
The turns ratio equals the square root of the impedance ratio, sqrt(8000 / 4) = sqrt(2000) approx 44.7, which means none of the standard options fit correctly.
Q4. Excavator machinery is frequently equipped with Ward-Leonard controlled D.C. drives primarily for _____________________ applications?
Show answer Hide answer
Answer: C. Heavy duty
Ward-Leonard controlled DC drives provide precise, wide-range speed control for heavy-duty applications. Excavator machinery requires massive torque at low speeds, which these robust DC drives deliver. The adjustable vol...
Q5. Separating two charges by a fixed distance while doubling the magnitude of each charge causes the electrostatic force to become_____________?
Show answer Hide answer
Answer: C. 4 times of its original value
Coulomb's law states that electrostatic force is proportional to the product of two charges. Doubling both charge magnitudes multiplies the numerator term by two times two. This mathematical operation increases the resul...
Q6. A circuit places two 1.2 kΩ resistors in series, and this series combination is wired in parallel with a 3.3 kΩ resistor; determine the total equivalent resistance____________?
Show answer Hide answer
Answer: B. 1,389 Ω
Two one point two kiloohm resistors in series add together to form a total of two point four kiloohms. Placing this two point four kiloohm combination in parallel with a three point three kiloohm resistor gives thirteen...