This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Force Determination”.
1. Which among the following, is the correct expression for force in a current carrying conductor if magnetic field is perpendicular to it?
a) F=Bi
b) F=B2il
c) F=Bil
d) F=Bl2
View Answer
Explanation: The correct expression for force in a current carrying conductor in a magnetic field perpendicular to it is F=Bil, where B is the magnetic field, i is the current in the conductor and l is the length of the conductor.
2. When the current in the current carrying conductor increases, what happens to the force in the conductor which is at right angles to the magnetic field?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer
Explanation: The force at right angles to the magnetic field of a current carrying conductor increases when the current increases because it is directly proportional to the force.
3. When the length of the conductor in the current carrying conductor increases, what happens to the force in the conductor which is at right angles to the magnetic field?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer
Explanation: The force at right angles to the magnetic field of a current carrying conductor increases when the length of the conductor increases because it is directly proportional to the force.
4. When the magnetic field intensity in the current carrying conductor increases, what happens to the force in the conductor which is at right angles to the magnetic field?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer
Explanation: The force at right angles to the magnetic field of a current carrying conductor increases when the magnetic field intensity increases because it is directly proportional to the force.
5. The unit for force in a current carrying conductor is _________
a) Tesla*Ampere*metre
b) Tesla
c) Ampere/metre
d) Ampere*metre
View Answer
Explanation: F=B*i*l. So,unit of force=unit of B * unit of i * unit of l = Tesla*Ampere*metre.
6. If net force is zero on a particle in magnetic field what is relation between velocity and magnetic field?
a) v=E*B
b) v=E/B
c) v=B/E
d) v=1/(E*B)
View Answer
Explanation: Since net force is zero on the particle.
Electric force = Magnetic force
QE = QvB => E=vB or v=E/B.
7. If the intensity of the magnetic field is 100T, the length of the conductor is 10m and the magnitude of force perpendicular to the magnetic field is 10kN,calculate the current in the conductor.
a) 100 A
b) 100 mA
c) 10 A
d) 10 mA
View Answer
Explanation: The formula for calculating the value of the force which is perpendicular to the magnetic field is:
F=Bil
Substituting the values from the question, we get i = 10A.
8. If the intensity of the magnetic field perpendicular to current carrying conductor is 100T, the length of the conductor is 3m and the current in the conductor is 10A, calculate the magnitude of force perpendicular to the electric field.
a) 300N
b) 30N
c) 30kN
d) 3kN
View Answer
Explanation: The formula for calculating the value of the force which is perpendicular to the magnetic field is:
F=Bil
Substituting the values from the question, we get F=3kN.
9. Force in current carrying conductor placed in magnetic field is ___________ of il and B.
a) dot product
b) scalar product
c) cross product
d) vector addition
View Answer
Explanation: Force in a current carrying conductor is given by cross product of il and B.
Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.
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