Magnetism & Electromagnetism Online Practice - Set 01 - ObjectiveBooks

# Practice Test: Question Set - 01

1. Fleming's left hand rule is used to find
(A) Direction of magnetic field due to current carrying conductor
(B) Direction of flux in a solenoid
(C) Direction of force on a current carrying conductor in a magnetic field
(D) Polarity of a magnetic pole

2. A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will
(A) Increase
(B) Decrease
(C) Remain constant
(D) Be excessive

3. The force between two long parallel conductors is inversely proportional to
(B) Current in one conductor
(C) Product of current in two conductors
(D) Distance between the conductors

4. What is the magneto-motive force in a 75-turn coil of wire when there are 4 A of current through it?
(A) 18.75 At
(B) 30 At
(C) 300 At
(D) 187 At

5. Substances which have permeability less than the permeability of free space are known as
(A) Ferromagnetic
(B) Paramagnetic
(C) Diamagnetic
(D) Bipolar

6. What is the magneto-motive force (mmf) of a wire with 8 turns carrying three amperes of current?
(A) 2,400 At
(B) 240 At
(C) 24 At
(D) 2.4 At

7. Which of the following is the unit of magnetic flux density?
(A) Weber
(B) Lumens
(C) Tesla
(D) None of the above

8. For a given wire-wound core, an increase in current through the coil
(A) Reverses the flux lines
(B) Decreases the flux density
(C) Increases the flux density
(D) Causes no change in flux density

9. When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon
(A) Resistance of the coil
(B) Motion of the magnet
(C) Number of turns of the coil
(D) Pole strength of the magnet

10. If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
(A) Increases
(B) Decreases
(C) Is zero
(D) Will remain constant

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