Physics Interview Questions and Answers

36 :: What is the difference between the Atomic Theory and the Kinetic Theory?

Atomic theory is about structure of an atom, i.e., its composition. Like an atom in general is made up of number of protons, neutrons residing in nucleus and electrons orbiting around the nucleus. However, kinetic theory deals with the manifestations of gases as molecules assuming that the volume occupied by molecules is negligible compared to the domain and the intermolecular force between molecules is also insignificant. Also assuming that there is a perfectly elastic collision between molecules and between molecules and wall, various macroscopic properties like pressure, temperature, enthalpy etc are derived. For example pressure exerted by gas on chamber walls can be derived by computing the momentum exchange of molecules with the wall. Thus apparently there is no similarity between the two above-mentioned theories.

Is This Answer Correct?    1 Yes 0 No

37 :: What are the branches of physics?

The fundamental branches of physics are classical mechanics, electromagnetism (including optics), relativity, thermodynamics, and quantum mechanics.

How was the length of a standard meter redefined in the year 1983?

Since 1983 the meter has been defined as the distance light travels in a vacuum in exactly 1⁄299,792,458th of a second

Is This Answer Correct?    1 Yes 0 No

38 :: What evidence is there supporting the Big Bang theory?

In short, the universe is expanding. All of the galaxies we have observed that are farthest away are moving away from us. And the farther away they are, the faster they are moving away. It took little imagination to "rewind" that picture and see a time when all of the matter and energy of the universe was basically "in one place" and there was no universe. With all the energy (matter could not have existed as we know it in an energy field so intense) in that one place after arriving or being created, a huge explosion, the Big Bang, created space-time.

The energy dispersed and, as things cooled down, matter began to form. It's the expanding universe that is the evidence for the Big Bang. That and the microwave background radiation that was discovered in the 1960's (and found to be everywhere) that is convincing. Here's an analogy (though not necessarily the best one) for the microwave background radiation. Imagine a cannon shell exploding in the air. After a few seconds, the blast is "all gone" but there is a cloud of smoke everywhere. The microwave background radiation is like the "leftover smoke" of the high (very, very, very high) energy event that was the blast of the Big Bang.

Is This Answer Correct?    1 Yes 0 No

39 :: Why does a glass filled with water shatter when you run your finger along the rim of the glass?

A piece of crystal stemware has a natural or resonant frequency that can be excited by rubbing a moistened finger along its rim. Filling the glass with water merely changes the pitch of the tone. The tone you hear is created when the crystal vibrates at frequencies in the audible range for humans. Although it's difficult to see, the glass actually flexes during the vibrations. If the glass deforms sufficiently, it can break, since crystal is brittle and not very elastic. It is not likely that a flawless glass could be made to break merely by rubbing its rim.

The Myth Busters demonstrated the resonance of a crystal glass and shattered several by exciting the glasses with a human voice. One professional singer broke a glass without the use of amplification. See the video.

Is This Answer Correct?    1 Yes 0 No

40 :: What is geocentric?

It is a science where the earth is the center of the solar system and the other planets and the sun revolve around the earth. However, most scientists say that we have the Heliocentric Model which (Helios) which means sun says that the sun is the center of the solar system and the planets revolve around the sun.

Is This Answer Correct?    1 Yes 0 No