21. What is the flux density in a magnetic field in which the flux in 0.1 m2 is 600 μWb?
(a) 6,000 μT
(b) 600 μT
(c) 600 T
(d) 6 T
22. What is the magnetomotive force in a 75-turn coil of wire when there are 4 A of current through it?
(a) 18.75 At
(b) 22 At
(c) 220 At
(d) 187 At
23. When the north poles of two bar magnets are brought close together, there will be ________.
(a) no force
(b) a downward force
(c) a force of attraction
(d) a force of repulsion
24. The direction of a magnetic field within a magnet is ________.
(a) from south to north
(b) from north to south
(c) back to front
(d) front to back
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5555555555 2. When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage ________. (a) increases (b) decreases (c) remains constant (d) reaches zero- 5555555555 5. If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density ________. (a) increases (b) decreases (c) remains the same (d) doubles
- 5555555555 16. 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
- 5555555555 20. When a solenoid is activated, the force that moves the plunger is ________. (a) an electromagnetic field (b) a permanent magnetic field (c) varying voltage (d) a steady current
- 5555555555 10. There is 900 mA of current through a wire with 40 turns. What is the reluctance of the circuit if the flux is 400 μWb? (a) 14,400 At/Wb (b) 1,440 At/Wb (c) 9,000 At/Wb (d) 90,000 At/Wb