Answer: When electricity flows through it.
Explanation:
The electromagnet exhibits magnetic properties only as soon as current flows through the nucleus. Namely, the electric current in the space around the electrical conductor through which it passes creates a magnetic field. Unlike a permanent magnet, which has a permanent property of magnetism, the electromagnet is a temporary magnet because the magnetic field also disappears when the current ceases.
Answer:
(a) Energy density will be equal to
(b) Total energy will be equal to 0.0718 J
Explanation:
It is given that length of solenoid l = 78.8 cm = 0.788 m
Cross sectional area
Number of turns of the wire N = 914
Current in the solenoid i = 8.25 A
Inductance of the wire is equal to
(b) Total energy stored in magnetic field
(a) Energy density will be equal to
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First convert the speed of sound from meters/second to miles/second:
Then the time it takes for the sound to travel 20 miles is