Question

in the circuit if the input voltage is 120 vp at 60 hz, what would the vdc be if a 100 uf capacitor was placed in parallel with the resistor?
3:1
120 v
rl = 4.7kω
select one:
○ a. 20 v
○ b. 40 v
○ c. 37.2 v
○ d. 38.3 v

Explanation:

Step1: Find Secondary Voltage

The transformer has a 3:1 ratio (primary:secondary). Primary voltage \( V_p = 120 \, \text{V} \). Secondary voltage \( V_{sec} = \frac{120}{3} = 40 \, \text{V (peak)} \).

Step2: Capacitor Filter Effect

When a capacitor is in parallel with the resistor (load) after a full - wave rectifier, the capacitor charges to the peak voltage of the rectified signal (for a well - filtered circuit, the DC voltage is approximately equal to the peak voltage of the secondary when the load is appropriate or the ripple is small enough). The peak secondary voltage is 40 V, so the VDC (with capacitor filter, assuming good filtering) is approximately equal to the peak secondary voltage, which is 40 V.

Answer:

b. 40 V