Free Alternating Current MCQs with Answers
592 Alternating Current MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Alternating current varies periodically, so phase relationships become essential when current passes through a resistor, capacitor or inductor. The chapter distinguishes resistance from capacitive and inductive reactance, explains phase lead and lag, and connects changing electric and magnetic fields with the production and properties of electromagnetic waves.
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Read the Alternating Current notesFree MDCAT chapter notes with key terms592 questions · page 4 of 30
- A. Both XC and XL are doubled
- B. Both XC and XL are halved
- C. XC is doubled and XL reduces to half
- D. XL is doubled and XC reduces to half
- E. Both XC and XL are unchanged
Explanation: The reactance of a capacitor is given by: Xc = 1/ (2πfC) where f is the frequency of the AC supply, and C is the capacitance of the…
Correct answer: XL is doubled and XC reduces to half- A. 30 degrees
- B. 45 degrees
- C. 60 degrees
- D. 90 degrees
- E. 180 degrees
Explanation: In an inverting amplifier configuration, the input signal is applied to the negative input terminal of the operational amplifier.
Correct answer: 180 degrees- A. 100 Hz
- B. 50 Hz
- C. 20 Hz
- D. 10 Hz
- E. 200 Hz
Explanation: The distance traveled by the wave along the X-axis in one complete cycle is the wavelength, which is given as 2 cm in the problem.
Correct answer: 50 Hz- A. 9V
- B. 18V
- C. 4.5V
- D. 0V
Explanation: Vp-p=2VpSubstituting the values from the question, we get Vp-p = 2(9)Vp-p = 18V
Correct answer: 18V- A. Period
- B. Cycle
- C. Instantaneous value
- D. Sin wave
Explanation: The duration of one cycle is known as the period. The period is the time it takes for a wave to complete one full cycle, which is…
Correct answer: Period- A. 0.5 x 10^-3 sec
- B. 0.5 second
- C. 5 sec
- D. 2 sec
Explanation: Formula: Frequency = 1/t t = 1/2000= 0.5 x 10-3 sec
Correct answer: 0.5 x 10^-3 sec- A. 2A
- B. A/√2
- C. 2√2A
- D. Zero
Explanation: The instantaneous current is given by I = A sin (wt). Here, A represents the peak current Imax.
Correct answer: A/√2- A. Visible light
- B. X rays
- C. Ultraviolet rays
- D. Gamma rays
Explanation: Reasoning:Energy of electromagnetic waves is directly proportional to their frequency and inversely proportional to their wavelength.
Correct answer: Gamma rays- A. X-rays
- B. Beta rays
- C. Gamma rays
- D. No radiation needs medium to travel
Explanation: Option D is correct because radiation does not need a physical medium to radiate. These radiate in the form of electromagnetic waves.
Correct answer: No radiation needs medium to travel- A. (velocity)2
- B. 1/velocity
- C. (velocity)1/2
- D. 1/velocity2
Explanation: The product μoεo has the same units as 1/velocity2.
Correct answer: 1/velocity2- A. 1.0 kWm-2
- B. 1.4 kWm-2
- C. 1.0 Wm-2
- D. 1.4 Wm-2
Explanation: The correct answer is 1.0 kWm-2 because this is the standard value of solar irradiance reaching the Earth's surface on a clear day at…
Correct answer: 1.0 kWm-2- A. Space waves
- B. Cable waves
- C. Antenna waves
- D. None of these
Explanation: Line-of-sight communication uses space waves, which travel directly from the transmitting antenna to the receiving antenna through the…
Correct answer: Space waves- A. V0=1.414 Vrms
- B. V0=10.10Vrms
- C. V0=10.70 Vrms
- D. Both A and B
Explanation: This statement is correct. V0 represents the peak value of an alternating voltage, while Vrms represents the root mean square (RMS) value…
Correct answer: V0=1.414 Vrms74. The phase difference between the current and voltage at resonance in R.L.C series A.C circuit is:
- A. 0
- B. -π/2
- C. -π
- D. π/2
Explanation: At resonance in an RLC series AC circuit, the inductive reactance (XL) and capacitive reactance (XC) are equal and cancel each other out.
Correct answer: 0- A. Very small
- B. Very large
- C. Zero
- D. Infinite
Explanation: The capacitive reactance in a pure capacitive DC circuit is infinite. This is because a steady DC voltage causes the capacitor to charge…
Correct answer: Infinite- A. Large
- B. Small
- C. Zero
- D. Infinite
Explanation: In a capacitive circuit, as the frequency increases, the capacitive reactance (Xc) decreases.
Correct answer: Large- A. Load
- B. Split rings
- C. Commutator
- D. Capacitor
Explanation: The component in a generator that consumes energy is called the load. In the context of electrical systems, a load is any device or…
Correct answer: Load- A. 7A
- B. 49A
- C. 7√2A
- D. 254A
Explanation: The mean square value (or RMS value) of an alternating current (AC) is given by the peak value divided by the square root of 2.Given that…
Correct answer: 7A- A. Current leads the voltage in a phase
- B. Current lags behind the voltage in a phase
- C. Current and voltage are in same phase
- D. Depends upon resistance
Explanation: Here is the explanation of the correct option Current and voltage vary sinusoidal with same frequency and are in phase with each other
Correct answer: Current and voltage are in same phase- A. zero.
- B. large.
- C. small.
- D. undetermined.
Explanation: at high frequencies, Xc becomes very small, allowing a large current to flow through the capacitor.
Correct answer: large.