Free Electromagnetism MCQs with Answers
1,176 Electromagnetism MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
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Read the Electromagnetism notesFree MDCAT chapter notes with key terms1,176 questions · page 15 of 59
- A. Armature
- B. magnet
- C. slip rings
- D. commutator
Explanation: D is the correct answer. A.C. generators do not have a commutator. A commutator is a component found in DC generators, which is…
Correct answer: commutator- A. (V/s). A
- B. N.m/A
- C. V^-1s.A
- D. V.s/A
Explanation: D is the correct answer. The henry (H) is the unit of inductance in the International System of Units (SI).
Correct answer: V.s/A- A. 1/2CV^2
- B. CV^2
- C. 2 CV^2
- D. 0
Explanation: In a pure capacitance, the current leads the voltage by 90 degrees, and the power is alternately absorbed and returned to the circuit.
Correct answer: 0284. The value of reverse current which is required by a substance for its demagnetization is called
- A. hysteresis loss
- B. remanence current
- C. coercive current
- D. relative current
Explanation: The coercive current, also known as the coercive force, is the reverse current required by a substance to demagnetize it completely after…
Correct answer: coercive current- A. once
- B. thrice
- C. twice
- D. 4 times
Explanation: In one period of an AC voltage source, the voltage completes one full cycle, going from positive to negative and back to positive.
Correct answer: twice- A. average value
- B. peak value
- C. rms value
- D. mean square value
Explanation: Most AC meters, such as ammeters and voltmeters, are calibrated to read the root mean square (rms) value of the alternating current or…
Correct answer: rms value- A. increases
- B. decreases
- C. increases or decreases depending upon AC frequency
- D. remains the same
Explanation: When a metal object is brought near the search coil of a metal detector, the inductance of the coil increases.
Correct answer: increases288. Choke coil has
- A. large resistance, small inductance
- B. large resistance, large inductance
- C. small resistance, small inductance
- D. small resistance, large inductance
Explanation: A choke coil, also known as an inductor, is a passive electrical component designed to oppose changes in current.
Correct answer: small resistance, large inductance- A. dipped in water
- B. brought near a piece of iron
- C. dipped in oil
- D. strongly heated
Explanation: Dipping magnetic materials in oil does not affect their magnetic properties.
Correct answer: dipped in oil- A. Will increase
- B. Will decrease
- C. Will not change
- D. None of the above
Explanation: In a step-up transformer, the secondary voltage V2 is greater than the primary voltage V1.
Correct answer: Will decrease- A. 1.6 x 10^-4
- B. 1.6 x 10^-8
- C. 1.6 x 10^-10
- D. 1.6 x 10^-11
Explanation: The force experienced by an electron in an electric field can be calculated using the formula:F= q.EWhere q= 1.6 x 10^-19 CE= 108 N/C
Correct answer: 1.6 x 10^-11- A. Collisions of free electrons with one another
- B. High drift speed of free electrons
- C. Collision of free electrons with atoms or ions of conductor
- D. High resistance value
Explanation: When an electric current flows through a conductor, it is primarily due to the movement of free electrons.
Correct answer: Collision of free electrons with atoms or ions of conductor- A. 9 x 10^-2 kg m2
- B. 8 x 10^-2 kg m2
- C. 5.33 x 10^-2 kg m2
- D. 12.2 x 10^-2 kg m2
Explanation: Relate the moment of inertia (I) to the time period (T) and magnetic moment (μ) for a magnet in a vibrating magnetometer:The equation…
Correct answer: 8 x 10^-2 kg m2- A. 3.6 x 10^-5T
- B. 1.84 x 10^-4T
- C. 2.56 x 10^-4T
- D. 5.8 x 10^-5T
Explanation: Recognize the situation:The problem deals with two short bar magnets placed on a horizontal table with their north poles pointing towards…
Correct answer: 2.56 x 10^-4T- A. V/e
- B. eV
- C. e/V
- D. V
Explanation: Work done and potential difference:The work done (W) on a charged particle by an electric field is related to the potential difference (V)…
Correct answer: eV- A. it does not draw any current
- B. it is very accurate
- C. it does not change circuit current considerably
- D. none of these
Explanation: This is the correct reason. A voltmeter is designed to measure the potential difference (voltage) between two points in a circuit.
Correct answer: it does not draw any current- A. a coil
- B. choke
- C. toroid
- D. none
Explanation: An inductor coil that consumes no energy is called a "choke" or an "inductive choke." A choke is an inductor designed specifically to…
Correct answer: choke- A. 25
- B. 50
- C. 100
- D. none
Explanation: In a full-wave rectifier circuit, the output waveform consists of both positive half-cycles of the input alternating current (AC) signal.
Correct answer: 100- A. Nm/A
- B. Nm²/A
- C. NA/m
- D. NA/m²
Explanation: The SI unit of magnetic flux is the Weber (Wb), which is equivalent to one Tesla multiplied by one square meter (1 T × 1 m²).
Correct answer: Nm/A- A. Increasing the number of turns per unit length
- B. Using a soft iron core
- C. Increasing the current
- D. All of these
Explanation: The magnetic field inside a solenoid is directly proportional to the current flowing through it.
Correct answer: Increasing the current