Free Electromagnetism MCQs with Answers

• A. 5V
• B. 10V
• C. 20V
• D. 50V

Explanation: We use the formula of motional emf. E = vBL = 5×2×0.5 = 5V

• A. Resistor
• B. Capacitor
• C. Inductor
• D. Thermistor

Explanation: Resistors (option a), capacitors (option b), and thermistors (option d) do not store magnetic potential energy in their components.

• A. Copper wire
• B. Silver wire
• C. Aluminum wire
• D. No physical connection between them

Explanation: In an AC motor, the stator and rotor are not physically connected. Instead, their interaction occurs through the electromagnetic fields…

• A. One wire two stators
• B. Two wires two stators
• C. Three wires two stators
• D. Three wires three stators

Explanation: A two-phase AC system uses three or four wires and has two stator windings in a motor, which are physically offset by 90 degrees.

• A. A.C. voltage
• B. D.C voltage
• C. A.C. as well as D.C
• D. Neither A.C. nor D.C

Explanation: Transformers work specifically with alternating current (AC). The basic principle of a transformer involves electromagnetic induction…

• A. Voltage
• B. Current
• C. Power
• D. Frequency

Explanation: The explanation of this question will be added soon!

• A. Input power > output power
• B. Input power < output power
• C. Input power = output power
• D. Output power = 0

Explanation: According to the principle of conservation of energy, an ideal transformer would ideally transfer all the power from the primary coil to…

• A. Smaller current and lower voltage
• B. Larger current and higher voltage
• C. Larger current and lower voltage
• D. Smaller current and higher voltage

Explanation: Option D is correct. This is the most efficient method for long-distance electrical power transmission.

• A. Reduce flux leakage
• B. Minimize hysteresis loss
• C. Decrease coil resistance
• D. Minimize eddy current

Explanation: Laminations are specifically designed to minimize eddy currents by breaking up the metallic core into insulated sheets.

• A. Flux should link the coil
• B. Change in flux should link the coil
• C. Coil should form a closed loop
• D. Both (b) and (c) are true

Explanation: The two conditions for inducing an EMF in a coil are that there must be a change in the magnetic flux linking the coil and that the coil…

• A. Transformer
• B. Dynamo
• C. AC generator
• D. None

Explanation: The emf is induced whenever a conductor is placed in the magnetic field of another conductor without having any relative motion.

• A. Anticlockwise
• B. Clockwise
• C. first anti-clockwise and then clo'ckwise
• D. First clockwise and then anti-clockwise

Explanation: By Lenz's law the direction of induced current in the ring is such as to oppose the falling of N-pole of the magnet.

• A. Current
• B. Power
• C. Voltage
• D. Heat

Explanation: So, in a step-up transformer, the quantity that remains constant (ideally) is B) Power.

• A. mechanical energy into electrical energy
• B. electrical energy into mechanical energy
• C. magnetic energy into electrical energy
• D. all of these

Explanation: Alternating current (AC) or voltage undergoes continuous variations in magnitude and regularly reverses its direction of flow.

• A. thickness of the wire in X
• B. resistance of X
• C. rate of change of magnetic field in X
• D. electric fields in X

Explanation: According to Faraday's law of electromagnetic induction, the electromotive force (EMF) induced in a coil is proportional to the rate of…

• A. move coil P toward coil Q
• B. open S
• C. move coil Q toward coil P
• D. move the slide of the rheostat R quickly to the right

Explanation: The energy stored in a magnetic field in an inductor is given by the formula W = LI2, where:* W is the energy stored,* L is the inductance…

• A. Current flowing
• B. Number of turns per unit length
• C. Voltage produced
• D. All of the above

Explanation: The self-inductance (L) of a coil depends on multiple factors:So, all of the options (a), (b), and (c) contribute to the self-inductance…

• A. An electric field only
• B. A magnetic field only
• C. Both an electric and magnetic field
• D. No such field at all

Explanation: A charge in uniform motion produces both an electric and magnetic field.

• A. Magnetic flux through the coil
• B. Rate of change of magnetic flux through the coil
• C. Area of the coil
• D. Product of magnetic flux and area of the coil

Explanation: Among the options given, the correct answer is A) Rate of change of magnetic flux through the coil.

• A. Enhance the magnetic flux
• B. Increase the weight
• C. Increase the copper loss
• D. Decrease the copper losses

Explanation: It helps to efficiently guide and increase the magnetic flux generated by the primary winding, allowing for effective induction of voltage…