For a circuit made up of a capacitance C and a resistance R, which expression gives its frequency?
Correct answer D. 1/RC
Subject / 3,947 questions
Everyday Science MCQs
Page 165 of Everyday Science multiple-choice questions with answers. Tap an option to check yourself.
Page 165 of 198
A coil develops an induced emf of 2 V when the current through it changes at 4 A s⁻¹. What is its self-inductance?
Correct answer C. 0.5 H
A pure inductor L and a pure capacitor C are connected in parallel across a sinusoidal potential difference V. How do the potential differences across L and C compare?
Correct answer D. They are the same
Advertisement
What does an ammeter connected in an AC circuit measure?
Correct answer B. RMS value of the current
A wire of resistance R is wound into a coil of inductance L. What is the impedance of the coil at frequency f?
Correct answer D. √(R² + 4π²f²L²)
A capacitor is connected in series with a lit bulb on an a.c. supply. What happens to the bulb’s brightness if a glass plate is inserted between the capacitor plates?
Correct answer A. It increases
A 100 µF capacitor is connected in series with a 12 V, 50 Hz source. Roughly what is its capacitive reactance?
Correct answer C. 32Ω
In a purely capacitive circuit, how is the current related to the voltage?
Correct answer C. It leads the voltage by π/2
When an alternating current passes through a capacitor, how are current and voltage related in phase?
Correct answer C. The current leads the voltage by 90°
Advertisement
In a purely resistive AC circuit, how are the voltage and current related?
Correct answer A. They have zero phase difference
An alternating current is given by I = I₀ sin πt. Which equation describes a current with twice the frequency and twice the amplitude?
Correct answer A. I = 2I₀ sin(2πt)
What must be calculated to find the r.m.s. value of an alternating current mathematically?
Correct answer D. Square root of the mean value of I²
An uncharged 30 µF capacitor is charged by a constant current of 10 mA. How long does it take for the potential difference across it to reach 300 V?
Correct answer A. 0.9 s
What type of waves are the electromagnetic waves radiated by an antenna?
Correct answer A. Transverse
What do electromagnetic waves transport?
Correct answer D. Energy
Advertisement
How is the direction of propagation of an electromagnetic wave related to its fields?
Correct answer C. Perpendicular to both electric and magnetic field
What does a changing magnetic flux induce?
Correct answer C. Electromotive force (emf)
An alternating current with an r.m.s. value of 4.0 A and frequency 50 Hz flows through a 10 Ω resistor. What is the peak current?
Correct answer A. 5.66 A
What is the steady current that produces heat in a resistor at the same rate as the mean heating rate of an alternating current called?
Correct answer A. r.m.s. current
If the capacitance in an L-C circuit is increased to four times its value, what happens to the frequency?
Correct answer D. One half