Physics Wave 10!!!

Q: What does it mean by wave transmits energy but not transferring matter?

Apart from electromagentic waves, mechanical waves, such as sound wave, water ripples or waves on a string, require a medium to propagate. In that sense, the energy of the waves is transmitted along the medium by vibration of moleucles of the medium. The medium itself doesn't move at all.

An example is the water ripples, if you throw a stone onto a pond of still water, you could observe that the ripples spreading out, but the water mass doesn't move along with the ripples.

Electromagentic waves, on the other hand, transmi energy by the time varying electric and magnetic fields.

Q: How's energy transmitted by wave and molecules?

As said above, energy is tranmitted from molecule to molecule through vibration of these molecules. You could imagine that the molecules are linked together as if there is an elastic spring joining them. When one molecule vibrates, the motion is transfered to the neighbouring molecules by the "elastic spring".

Q: What makes the water molecules next to it to oscillate?
This has been explained in the last question. The efefct of "elastic spring" so mentioned is, in fact, played by intermolecular force. This is an attractive force acting among molecules holding them together.

You could try to have a look on the following animation. It can be played in slow-motion, first by pressing the "start" and then "stop" buttons, then pressing the '>>" buttion.

http://www.cbu.edu/~jvarrian/applets/waves1/lontra_g.htm