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One of the ways in which a coin operated vending machine checks tomake sure that

ID: 1727906 • Letter: O

Question

One of the ways in which a coin operated vending machine checks tomake sure that the coins fed to it are genuine is to roll them pasta strong magnet.
A)Only coins made of magnetic materialssuch as iron will be affected by the magnet.
B)Coins made of a good conductor will speed upas they roll past the magnet.
C)Coins made of a good conductor will slow downas they roll past the magnet.
D)The coins will become magnetized and thus caneasily be sorted. Hint:
The conducting plate isreplaced by a conducting coin.
A)Only coins made of magnetic materialssuch as iron will be affected by the magnet.
B)Coins made of a good conductor will speed upas they roll past the magnet.
C)Coins made of a good conductor will slow downas they roll past the magnet.
D)The coins will become magnetized and thus caneasily be sorted. Hint:
The conducting plate isreplaced by a conducting coin. Hint:
The conducting plate isreplaced by a conducting coin.

Explanation / Answer


The induced currents in the coin due to moving a conductorthrough a magnetic field will cause a force that tends to workagainst the movement, slowing down the coin. Answer C
Another application of this is used in a good scale, like atriple beam balance. The scale will often have a flat plateat the end of the beams that moves up and down between the poles ofa magnet. This will tend to dampen out the bouncing of thescale. Look at one the next time you can.