Math Problem Statement

Can you solve this problem?

Can you solve this problem?

Solution

The circuit diagram shows a step-down transformer connected to a rectifier with a filter capacitor and load resistor. Let me break it down and solve for the quantities indicated. Here’s what the setup looks like:

Components:

  1. Transformer: The input voltage is 220V AC, and the transformer steps it down with a turns ratio NpNs\frac{N_p}{N_s}.
  2. Bridge Rectifier (Si): Converts the AC from the transformer to pulsating DC.
  3. Capacitor (C = 100μF): Smooths the DC output from the rectifier.
  4. Load Resistor (R_L = 1kΩ): The final load across the capacitor.
  5. Resistor Ri=0.1ΩR_i = 0.1 \, \Omega is the internal resistance.

Quantities we need to calculate:

  • VoV_o (output voltage),
  • IoI_o (output current),
  • Transformer’s primary (Np) and secondary (Ns) turns ratio,
  • Vr(rms)V_{r(rms)} (ripple voltage),
  • VsV_s (secondary voltage),
  • VmV_m (peak voltage),
  • JxJ_x, JsJ_s, etc.

I will first outline the general steps to solve the circuit:

  1. Transformer secondary voltage VsV_s: Using the turns ratio: VpVs=NpNs\frac{V_p}{V_s} = \frac{N_p}{N_s} We can calculate the secondary voltage once we have the turns ratio NpNs\frac{N_p}{N_s}.

  2. Rectified DC output voltage VoV_o: The output voltage after the bridge rectifier will be approximately: VoVs22VdiodeV_o \approx \frac{V_{s}}{\sqrt{2}} - 2V_{diode} where VdiodeV_{diode} is the forward voltage drop across each diode (typically 0.7V for Si diodes).

  3. Ripple voltage Vr(rms)V_{r(rms)}: The ripple voltage after the filter capacitor can be approximated as: VrIofCV_r \approx \frac{I_o}{fC} where ff is the frequency of the rectified output (which is typically twice the input AC frequency, so 100 Hz for 50 Hz AC), and IoI_o is the load current.

  4. Load current IoI_o: The load current is simply: Io=VoRLI_o = \frac{V_o}{R_L}

Let me now calculate the quantities. I will start by assuming standard values for some missing details.Here are the calculated values for the circuit:

  1. Secondary AC voltage VsV_s: 22V
  2. Peak secondary voltage VmV_m: 31.11V
  3. Rectified DC output voltage VoV_o: 20.6V
  4. Load current IoI_o: 0.0206A (20.6mA)
  5. Ripple voltage Vr(rms)V_{r(rms)}: 2.06V

Circuit Operation (in less than 100 words):

This circuit uses a step-down transformer to convert 220V AC to 22V AC. A bridge rectifier then converts this AC to pulsating DC. The output is smoothed by a 100μF capacitor, but some ripple remains, calculated to be 2.06V. The final DC voltage across the load is about 20.6V. The resistor RLR_L limits the current through the load to 20.6mA. The internal resistance of 0.1Ω has minimal impact due to its small value.


Would you like to dive deeper into any of the steps or values?

Related Questions:

  1. How does the turns ratio affect the output voltage?
  2. What would happen if the load resistor was increased?
  3. How can you reduce ripple voltage further?
  4. How does the capacitor value influence the ripple?
  5. What is the role of the internal resistance RiR_i in this circuit?

Tip: Increasing the capacitance or load resistance can help reduce ripple voltage in DC power supplies.

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Math Problem Analysis

Mathematical Concepts

AC to DC conversion
Rectifier circuit
Ripple voltage
Transformer turns ratio

Formulas

Vo ≈ Vm - 2Vdiode
I_o = Vo / R_L
V_r ≈ I_o / (f * C)
V_s = V_p * (N_s / N_p)

Theorems

Ohm's Law
Transformer Turns Ratio Theorem
Ripple Voltage Calculation for a Capacitor

Suitable Grade Level

Undergraduate Electrical Engineering