Problem + Hard 53-1    Source:  Problem prepared by the author of the site.

Determine, based on the figure below, the values ​​of:

a) the current I;

b) the voltages V_b and V_c.

Problem + Hard 53-2    Source:   exercise 8-21 - page 407 - THOMAS, Roland E., ROSA, Albert J. , THOUSSAINT, Gregory J. -   Book: The Analysis & Design of Linear Circuits - 6th Edition - Ed. John Willey & Sons, Inc. - 2009.

Using superposition find the voltage V_o(t) in the circuit shown in the figure below, knowing that:      i₁(t) = 100 cos(10,000t) mA      and      v₁(t) = 20 cos(20,000t - 45°) V.

Problem + Hard 53-3    Source:   2nd question - page 10 - BORDINI, Sergio Machado -   Book: Circuit: Solving Problems - 1st Edition - Manuscript (621.3.049.B729c, Eng. Ufrgs Library).

In the circuit shown in the figure below we have an impedance Z of unknown nature. To find it, two readings were taken on the voltmeters where V₁ = 30 volts and V₂ = 90 volts. It is known that I₁ is ahead of a E₁. Determine the impedance Z.