MDCAT ECAT Physics MCQs with Answers – All Units – Page 7

Question 121 Electronics

A full-wave rectifier built with only two diodes requires which additional component?

Correct answer D. A centre-tapped transformer

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Question 122 Electronics

In a bridge rectifier, how many diodes conduct during any one half-cycle of the input?

Correct answer D. Two

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Question 123 Alternating Current

A 0.50 H inductor of negligible resistance is connected to a 230 V, 50 Hz supply. What rms current flows?

Correct answer B. 1.5 A

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Question 124 Alternating Current

Which list places the following electromagnetic waves in order of increasing frequency?

Correct answer B. Radio waves, microwaves, infrared, ultraviolet, X-rays

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Question 125 Alternating Current

Which part of the electromagnetic spectrum has the shortest wavelength?

Correct answer A. Gamma rays

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Question 126 Alternating Current

Which statement about electromagnetic waves travelling in a vacuum is correct?

Correct answer B. All travel at the same speed of about 3.0 × 10⁸ m/s

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Question 127 Alternating Current

An FM radio station broadcasts at 100 MHz. Take c = 3.0 × 10⁸ m/s. What is the wavelength of its waves?

Correct answer C. 3.0 m

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Question 128 Alternating Current

Which electromagnetic radiation is produced when fast-moving electrons strike a heavy metal target?

Correct answer C. X-rays

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Question 129 Alternating Current

Which region of the electromagnetic spectrum is mainly emitted by warm objects and used in thermal imaging cameras?

Correct answer D. Infrared

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Question 130 Alternating Current

Which statement best describes an electromagnetic wave?

Correct answer B. Oscillating electric and magnetic fields perpendicular to each other and to the direction of travel

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Question 131 Alternating Current

Light of wavelength 600 nm travels in a vacuum. Take c = 3.0 × 10⁸ m/s. What is its frequency?

Correct answer B. 5.0 × 10¹⁴ Hz

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Question 132 Alternating Current

Which region of the electromagnetic spectrum lies between infrared and radio waves?

Correct answer D. Microwaves

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Question 133 Alternating Current

A capacitor of reactance 115 Ω is connected to a 230 V rms AC supply. What rms current flows?

Correct answer D. 2.0 A

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Question 134 Alternating Current

At what frequency does a 0.50 H inductor have a reactance of 100 Ω?

Correct answer B. 31.8 Hz

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Question 135 Alternating Current

In a series RLC circuit, what is the phase difference between the voltage across the inductor and the voltage across the capacitor?

Correct answer A. 180°

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Question 136 Alternating Current

Two alternating voltages of the same frequency are such that one reaches its peak a quarter of a period after the other. What is the phase difference between them?

Correct answer D. 90°

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Question 137 Alternating Current

For a 50 Hz supply, what time delay corresponds to a phase difference of π/2 rad?

Correct answer B. 5.0 ms

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Question 138 Alternating Current

An alternating voltage is given by V = 200 sin(100πt), with V in volts and t in seconds. What is its frequency?

Correct answer D. 50 Hz

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Question 139 Alternating Current

The rms value of an alternating current is defined as the value of the steady direct current that ____.

Correct answer B. produces the same heating effect in a given resistor

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Question 140 Alternating Current

A sinusoidal voltage of peak value 100 V is applied across a 50 Ω resistor. What is the average power dissipated?

Correct answer D. 100 W

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