A quantity of water at 0°C is heated to about 30°C. At each degree rise in temperature, its density will

I. Coherence
II. Same frequency
III. Same wavelength
IV. Same Intensity

Which of the conditions above are necessary to produce interference fringes?

A thin wire with heavy weights attached to both ends is hung over a block of ice resting on two supports. If the wire cuts through the ice block while the block remains solid behind the wire, the process is called

Dry
Day 1 - 30°C | Day 2 - 29°C | Day 3 - 25°C

Wet
Day 1 - 22°C | Day 2 - 22°C | Day 3 - 21°C

The reading above are for three consecutive days from a wet and dry bulb hygrometer. It can be concluded that the relative humidity for the three days