Prabin Kalikote

a. Principal axis:
The line joining both the centers of curvatureof a lens is called the principal axis.

b.Optical center:
The geometrical center of a lens is known asits optical center.

c. Center of curvature:
The center of the sphere from whichthe lens has been cut is called the center of curvature.

d. Focal length:
The distance between principle focus andoptical center is called the focal length.

e. Far point:
The distance point from the eyeseen clearly is called the far point.

f. Near point:
The...

The different types of lens are:

Convex lens: A lens that is thick in the middleand thin at the edge is called aconvex lens.

Concave lens: A lens that is thick at the edgesbut thin in the middle is called aconcave lens.

A lens is a piece of transparent glass bounded bytwo refracting surfaces which are usually spherical.

Two uses of the lens are:

1. It is used in the human spectacle.
2. It is used in scientific projects.
   

It means one kilogram mass of B requires 470J of heat to raise its temp. by 1⁰C.

C will have the highest temperature because it has the lowest sp. heat capacity and B will have the lowest temperature because it has the highest sp. heat capacity.
From: sp. heat capacity1/temperature.

B will make the deepest hole in the wax slab because it has more heat to release to the wax slab as it is with constant mass and temp. with the highest sp. heat capacity.

A new quilt has high air storage capacity as it is thickerthan the old one, But the old quilt can't store moreair as it is compressed by several uses. So, a new quiltacts as a better insulator than the old one. So, a new quiltprevents our body's heat to be released into the atmosphere in a better way than the old one. Hence, a new quilt is warmer than an old one.

In the winter season, the morning temp. on the earth's surface is very low. But the inner core of the earth is always hot. We know, well water is absorbed from deep inside the ground. At that surface, water absorbs the heat from the earth's core and remains hot. When the same water is brought to the surface, the temp. of water is higher than that of surroundings. So, well water is felt to be warmer in the morning during the winter.

We all know that water has the highest specific heatcapacity. So, it absorbs more heat and also loses moreheat. During the day, the heat near the sea area is absorbedby water in the sea and during the night the area near the seaabsorbs heat from the sea.
So, the temp near the searemains moderate.