Physics Interview Questions and Answers

31 :: How do you magnetize metal?

You can rub a magnet along the metal in one direction for a bunch of times (the more the better), and that will magnetize it to some degree, but it’s not permanent and will demagnetize if it is hit hard with something.

Also, to magnetize something like a nail, if you point one end north, and hit the other end with a hammer it should weakly magnetize it. Unfortunately it doesn't work every time.

Links are provided to Wikipedia and a couple of other sources.

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32 :: What are isotopes?

An atom of an element that has a different number of neutrons in its nucleus to other atoms of the element

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33 :: Why does heat cause matter to expand?

Water contracts as it cools, like all other liquids, until it reaches a temperature of about 4 degrees Celsius, at which point it expands and begins to form into crystals, expanding approximately 9 percent.

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34 :: How does laser printer works?

When a text or image is entered into the CPU, it produces a series of varying voltages. This controls a LED (light emitting diode) in the printer. This emits flashes of laser, when it falls on a charged photo conducting drum. The area corresponds the text or image will either be neutralized or oppositely charged. A toner which has the same charge as the background is sprayed onto it. It only sticks to the text or image and is repelled by the background. A fresh paper is now pressed onto the toner and is slightly heated so that it sticks firmly on the paper....

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35 :: What is parallel force?

Parallel forces are two or more forces which act in parallel. The forces do not have to be in the same direction however.

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