RL circuits (AC)

Problem:

A large AC electric motor under load can be considered as a parallel combination of resistance and inductance.  If the equivalent resistance is 20 Ω and the inductance is 238 mH, calculate the rms current delivered by the 60 Hz, Vrms = 240 V AC power supply.

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Solution:

Problem:

In an AC circuit, a filter circuit or filter removes unwanted frequency components from an input.  A passive filter consists of a circuit with at least one reactive component.  A filter with a single reactive component, either a capacitor or an inductor, is called a first-order filter.  Filters are described according to their behavior.  A low-pass filter will pass all signals below a specific frequency, but will attenuate or block signals of a higher frequency.  A high-pass filter will do just the opposite.  The boundary line is somewhat arbitrary since there exists a "transition zone".  The cutoff frequency is defined as the frequency at which |Vout| = 2|Vin|.
Inspect the filter shown below.  Identify what type of filter this circuit is, and calculate the size of resistor necessary to give it a cutoff frequency of 3 kHz:

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Solution: