9702_s07_qp_4

[XPFMember]

Assalamoalaikum warehmatullahi wabarakatuh!

Can anyone help me with Q:7 (c) of June:2007 Paper:4

Jazak Allah Khair!

 

[destined007]

Here:

 

[XPFMember]

JazakALlah Khair...third part too..please

 

[destined007]

Microwave oven:
Many molecules (such as those of water) are electric dipoles, meaning that they have a partial positive charge at one end and a partial negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. Rotating molecules hit other molecules and put them into motion, thus dispersing energy. This energy, when dispersed as molecular vibration in solids and liquids (i.e., as both potential energy and kinetic energy of atoms), is heat. (they won't ask you this. Just for your information)

Bridges:
because resonance leads to maximum amplitude, there is a danger of bridge collapsing.