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 49 of 59
- A. Magnetically linked
- B. Electrically linked
- C. Both A and B
- D. Isolated with each other
Explanation: The explanation is: The magnetic flux of the primary coil is linked with the secondary coil.When current flows through the primary coil…
Correct answer: Magnetically linked- A. Zero
- B. I2R
- C. One
- D. V2I
Explanation: The explanation is: The average value of alternating voltage or alternating current over a cycle is zero, but the power delivered in one…
Correct answer: I2R- A. The power in the primary circuit is less than that in the secondary circuit
- B. The currents in the two circuits are the same
- C. The voltages in the two circuits are the same
- D. The primary current is six times the secondary current
Explanation: In this transformer, the primary coil has 100 turns and the secondary coil has 600 turns.
Correct answer: The primary current is six times the secondary current- A. 25,600V
- B. 3200V
- C. 400V
- D. 50V
Explanation: In a transformer, the power in the primary side equals the power in the secondary side (ignoring losses).
Correct answer: 3200V- A. Input current same as output current
- B. Output voltage lower than input voltage
- C. Output current higher than input current
- D. Output current lower than input current
Explanation: A transformer in which voltage across secondary is less than the primary is called a step down transformer.
Correct answer: Output voltage lower than input voltage- A. 1ms-1
- B. 2ms-1
- C. 4ms-1
- D. 8ms-1
Explanation: Explanation is given below: The electromotive force (emf) induced in a conductor moving at right angles to a magnetic field can be…
Correct answer: 4ms-1- A. Using primary and secondary wires of less resistance
- B. Making the sheets of transformer core fully insulated
- C. Using methods to increase the flux coupling between the coils
- D. All of these
Explanation: In order to improve the efficiency, to minimize all the power losses: Core should be assembled from the laminated sheets of a material…
Correct answer: All of these- A. Using stronger magnetic field
- B. Replacing loop by a coil of many turns
- C. Moving the loop faster
- D. All of these
Explanation: The induced current can be increased by: i. Using a strong magnetic field. ii. Moving the loop faster. iii.
Correct answer: All of these- A. 0.1Wb
- B. 0.2Wb
- C. 0.3Wb
- D. 0.4Wb
Explanation: The formula is ΦB=BAcos Ɵ, Area =0.2x0.5=0.1m2 ΦB=BAcos0=(2)(0.1)=0.2Wb
Correct answer: 0.2Wb- A. Input and output power is same
- B. Currents are inversely proportional to voltage
- C. Currents are directly proportional to voltage
- D. Both "A" and "B"
Explanation: For an ideal transformer: Power Input = Power Output
Correct answer: Both "A" and "B"- A. 10A
- B. 0.01A
- C. 100A
- D. 0.1A
Explanation: In a step-down transformer, the current and voltage are related by the turns ratio as follows:Transformer Current Formula:Iₚ × Nₚ = Iₛ ×…
Correct answer: 100A- A. Induced emf
- B. Induced current
- C. Magnetic flux
- D. magnetic induction
Explanation: The direction of induced current is always so as to oppose the change which causes the current Lenz's law refers to induced current not…
Correct answer: Induced current- A. 0.5V
- B. 3V
- C. Zero
- D. 3.5V
Explanation: When loop is placed parallel to changing magnetic field, then the angle between magnetic field and vector area is 90o.
Correct answer: Zero- A. Back emf
- B. Motional emf
- C. Directional emf
- D. Statically induced emf
Explanation: The emf induced by the motion of a conductor across a magnetic field is called motional emf.
Correct answer: Motional emf- A. Vs/Vp>Ip/Is
- B. Ps/Pp>I
- C. Ip/Is>I
- D. All of these
Explanation: A transformer in which voltage across the secondary is greater than the primary is called a step-up transformer Vs>Vp and Ns>Np and Ip>Is.
Correct answer: Ip/Is>I- A. Output voltage = Input voltage
- B. Output power = Input power
- C. Output current = Input current
- D. Output energy = Input energy
Explanation: For an ideal transformer (100% efficiency) Power input = Power output
Correct answer: Output power = Input power- A. vBLsin0
- B. vBL
- C. Zero
- D. NωABsinθ
Explanation: As glass is an insulator. So, there no free charges in the glass rod to produce an induce emf.
Correct answer: Zero- A. Equal to input
- B. More than input
- C. Less then input
- D. Infinity
Explanation: For an ideal transformer: Power Input = Power Output But in case of actual transformer Power Input > Power Output.
Correct answer: Less then input- A. V=Vosin(2πft)
- B. V=Vosin(2πωft)
- C. V=Vosin(2ft)
- D. V=Vosin(ft)
Explanation: Instantaneous value of current and voltage is V = Vosin (2πft) and I = 1o sin (2πft) respectively
Correct answer: V=Vosin(2πft)- A. Its magnitude as well as direction
- B. Only magnitude but not direction
- C. Only direction but not magnitude
- D. Both remains same
Explanation: Alternating current changes its magnitude as well as direction.
Correct answer: Its magnitude as well as direction