Module 2 Flashcards
states that the induced current in a loop is in the direction that creates a magnetic field that opposes the change in magnetic flux through the area enclosed by the loop
Lenz’s Law
When the north pole of the magnet is approaching towards the coil, the magnetic flux linking to the coil ___
increases
When the north pole of the magnet is moving away from the coil, the magnetic flux linking to the coil _____
decreases
Now according to Lenz’s law, this magnetic field created will oppose its own or opposes the increase in flux through the coil and this is possible only if the approaching coil side attains ____.
north polarity
Now according to Lenz’s law, this magnetic field created will oppose its own or opposes the decrease in flux through the coil and this is possible only if the approaching coil side attains _____.
south polarity
used for finding the directions of magnetic field or current
right-hand thumb rule
A loop of conducting wire with length L and width W is entering a
magnetic field B at velocity v. What direction will the induced current
travel in?
A. clockwise
B. counterclockwise
C. up
D. down
B
What is the direction of the magnetic force on the loop as it enters magnetic field B?
A. up
B. down
C. right
D. left
D
What is the direction of the magnetic force on the loop as it leaves magnetic field B?
A. up
B. down
C. right
D. left
D
Why do you need to swipe your credit card in the credit card reader for it to accept your charge?
A. The magnetic field in the reader only works when the credit card is
moving
B. The current in the reader flows when the credit card strip is
stationary
C. The magnetic field in the credit card strip needs to move to induce a current in the reader
D. The magnetic field in the credit card strip only exists when it is
moving
C
Which of the following laws is used to find the direction of the induced
current in a loop of wire placed in a changing magnetic field?
A. Len’s Law
B. Faraday’s Law
C. Ampere’s Law
D. Gauss’s Law
A
Lenz devised a rule to find out the direction of which quantity?
A. current induced in a circuit
B. electromagnetic difference
C. potential difference
D. flow of power
A
What is the direction of an induced current?
A. opposes the cause
B. remains the same as the cause
C. equal to the cause that produces it
D. directs the cause
A
A magnet is dropped into a long copper tube with its North pole facing downwards. As the North pole approaches the top end of the tube, which way will the current flow when viewed from above the top of the tube?
A. The current will flow counterclockwise, creating a magnetic field pointing upwards, opposing the North pole moving downwards.
B. The current will flow clockwise, creating a magnetic field pointing upwards, opposing the North pole moving downwards
C. The current will flow counterclockwise, creating a magnetic field pointing downwards, opposing the North pole moving downwards.
D. The current will flow clockwise, creating a magnetic field pointing downwards, opposing the North pole falling down.
A
A strong permanent magnet is plunged into a coil and left in the coil. What is the effect produced on the coil after a short time?
A. The coil winding becomes hot
B. The insulation of the coil burns out
C. A high voltage is induced
D. There is no effect
D
