Direct and alternating current Quiz 1

Question 1

A peak value of current $${{I}_{0}}=0.55\ A$$ flows through an LCR circuit of resistance $$R=200\Omega $$, inductive reactance $${{X}_{L}}=300\Omega $$ and capacitive reactance $${{X}_{C}}=400\Omega $$. Determine the magnitude of the peak supply voltage.

Accepted Answer

$$123\ V$$

Answer

$$110\ V$$

Answer

$$165\ V$$

Answer

$$220\ V$$

Question 2

The wiring of a lighthouse's searchlight beacon is shown in the diagram below. Determine how much current is flowing through the searchlight at any given moment. What is the circuit's impedance?<img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/7b6b0a3b-98e9-408e-987c-f6df41407dd71757525035228291518.png"/>

Accepted Answer

$$0.3535\ A$$, $$800\Omega $$

Answer

$$0.25\ A$$, $$80\Omega $$

Answer

$$0.25\ A$$, $$56\Omega $$

Answer

$$0.3535\ A$$, $$80\Omega $$

Question 3

Consider the following oscillating circuit that is used to tune the radio frequency of an AM/FM radio. The voltage drops across the current elements are $${{V}_{L}}=50\ V$$, $${{V}_{C}}=80\ V$$ and $${{V}_{R}}=40\ V$$ respectively. What is the voltage of the alternator used?<img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/9637994d-abbd-4c78-a108-d8cd5aa389d26203373497936057364.png"/>

Accepted Answer

$$50\ V$$

Answer

$$30\ V$$

Answer

$$40\ V$$

Answer

$$90\ V$$

Question 4

The admittance of a series $$LR$$ circuit is found to be $$2	imes {{10}^{-3}}\ {{\Omega }^{-1}}$$.Determine the angular frequency of oscillation of this circuit, given $$L=0.5\ H$$ and $$R=100\Omega $$.

Accepted Answer

$$980\ {{s}^{-1}}$$

Answer

$$150\ {{s}^{-1}}$$

Answer

$$490\ {{s}^{-1}}$$

Answer

$$98\ {{s}^{-1}}$$

Question 5

When a charged capacitor is connected to an inductor, both the current and the charge on the capacitor oscillate. In the given figure, a capacitor is initially charged when $${{K}_{1}}$$ is open and $${{K}_{2}}$$ is closed. Then $${{K}_{1}}$$ is closed and $${{K}_{2}}$$ is opened such that the capacitor is shorted across the inductor. Determine $$\$$ i) The maximum value of charge on the capacitor. $$\$$ ii) The maximum value of current in the circuit. $$\$$ iii) What would be the resultant equation of current as a function of time?<img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/2975d63a-0474-447a-9100-aa4369b58e5a1793021638401234722.png"/>

Accepted Answer

$$1.08	imes {{10}^{-10}}\ C$$, $$6.79	imes {{10}^{-4}}\ A$$ and $$-(6.79	imes {{10}^{-4}})\ sin(\omega t)$$

Answer

$$1.08	imes {{10}^{-10}}\ C$$, $$6.79	imes {{10}^{-4}}\ A$$ and $$-(6.79	imes {{10}^{-4}})\ cos(\omega t)$$

Answer

$$0.75	imes {{10}^{-12}}\ C$$, $$4.72	imes {{10}^{-6}}\ A$$ and $$-(4.72	imes {{10}^{-6}})\ sin(\omega t)$$

Answer

$$0.75	imes {{10}^{-12}}\ C$$, $$4.72	imes {{10}^{-6}}\ A$$ and $$-(4.72	imes {{10}^{-6}})\ cos(\omega t)$$