Recent content by Alan Tam

As in the following link of diffraction grating experiment: http://www.practicalphysics.org/go/Experiment_120.html?topic_id=1&collection_id=20 To derive the diffraction gratig formula, we assume the rays emerging from the slits are parallel which requires the screen to be far from the...

We look at a lamp at a distance through a slit form the halves of a broken razor blade and a diffraction pattern is observed. My questions are: 1. Is it a Fraunhofer diffraction? Our eyes are close to the slit, but one of the conditions for fraunhofer diffraction to occur is the screen...

Many Physics books state that mass is the quantity of matter. What does the "matter" refer to? Objects contain the same number of particles could still have different masses. Could anyone help me? Thanks.

Dear Warren, you mean the amount of water vapour in the bus have to reach certain level in order to condense? If the temperature in the bus is further reduced, will the water vapour condense eventally? Alan

We should have experience that when we get off from an air-conditioned bus in the summer, our glasses become misty. It's due to condensation of water vapour on our cooler glasses. But why the condensation doesn't occur in the air-conditioned bus?

Why does copper conduct heat better than aluminium and iron? Could anyone help me answering the question? Thanks.

Rephrasing my question Sorry, I mean, why a black surface absorbs much incident radiant energy than a silvery surface?

Could anyone help me answering the above question? Thanks.