Question

A CRO probe has an impedance of $500k\Omega$ in parallel with a capacitance of $10\mu F$. The probe is used to measure the voltage between P and Q as shown in figure. The measured voltage will be

• A. 3.53 V
• B. 4.37 V
• C. 4.54 V
• D. 5.00 V

Answer 1

The correct option is B 4.37 V

$X_c=\frac{1}{2\pi fC}$
$=\frac{1}{2\times \pi \times {10}^3\times 100\times 10\times {10}^{-12}}=159.15k\Omega$


Taking supply voltage as the refrence.

$V_s=10\angle 0V$

Using KCL,

$\frac{V_p-10}{100\times {10}^3}+\frac{V_p}{100\times {10}^3}+\frac{V_p}{500\times {10}^3}+\frac{V_p}{-j159.15\times {10}^3=0}$

$V_p=4.37\angle -{15.94}^{\circ }V$