Math Problem Statement

Assuming a practical model, for the Rectifier circuit shown, determine the output current across the load, R. The transformer Vsec = 12 Vrms. R = 10K ohms.

Solution

The circuit shown in the image is a full-wave bridge rectifier, which consists of four diodes (D1, D2, D3, and D4) and a load resistor RR. The transformer provides an AC voltage at the secondary side with a given VSEC=12VrmsV_{SEC} = 12 \, \text{V}_{\text{rms}}. The load resistor RR is 10kΩ10 \, \text{k}\Omega.

Steps to solve for the output current:

  1. Peak Voltage at the Secondary: The RMS value VSECV_{\text{SEC}} is related to the peak value VpeakV_{\text{peak}} by: Vpeak=VSEC×2=12×216.97VV_{\text{peak}} = V_{\text{SEC}} \times \sqrt{2} = 12 \times \sqrt{2} \approx 16.97 \, \text{V}

  2. Voltage Drop across the Diodes: In a bridge rectifier, during each half-cycle, two diodes conduct. Each diode has a typical forward voltage drop of about 0.7V0.7 \, \text{V}. Therefore, the total voltage drop due to the diodes is: Vdiodes=2×0.7=1.4VV_{\text{diodes}} = 2 \times 0.7 = 1.4 \, \text{V}

  3. Output DC Voltage: The output voltage across the load RR is the peak secondary voltage minus the voltage drop across the diodes: Vout=VpeakVdiodes=16.97V1.4V=15.57VV_{\text{out}} = V_{\text{peak}} - V_{\text{diodes}} = 16.97 \, \text{V} - 1.4 \, \text{V} = 15.57 \, \text{V}

  4. Output Current through the Load: The current IoutI_{\text{out}} through the load resistor RR can be found using Ohm's law: Iout=VoutR=15.57V10×103Ω1.557mAI_{\text{out}} = \frac{V_{\text{out}}}{R} = \frac{15.57 \, \text{V}}{10 \times 10^3 \, \Omega} \approx 1.557 \, \text{mA}

Final Answer:

The output current across the load resistor RR is approximately 1.557mA1.557 \, \text{mA}.

Would you like further details or have any questions?

Related Questions:

  1. What happens if the load resistor RR is decreased?
  2. How does the peak inverse voltage (PIV) of each diode affect the circuit?
  3. What is the output voltage ripple if a capacitor is added in parallel with the load?
  4. How would increasing the forward voltage drop of the diodes affect the output current?
  5. Can this circuit be used for higher power applications, and what modifications are needed?

Tip: Always check the peak inverse voltage (PIV) rating of diodes in a rectifier circuit to ensure they can handle the reverse voltage without breaking down.

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Math Problem Analysis

Mathematical Concepts

AC-DC Conversion
Rectifier Circuit
Ohm's Law

Formulas

Vpeak = Vrms * sqrt(2)
Vout = Vpeak - Vdiodes
Iout = Vout / R

Theorems

Ohm's Law
Bridge Rectifier Diode Voltage Drop

Suitable Grade Level

Undergraduate Electrical Engineering