This document provides definitions and explanations related to spheres. It defines a sphere as a solid generated by revolving a semicircle about its diameter. It lists examples of spheres from daily life like balls and globes. It explains that the diameter of a sphere passes through its center and that the center and radius of the semicircle used to generate the sphere are also the center and radius of the sphere. It defines a hemisphere as half of a sphere divided by a plane passing through the center. It provides formulas for the surface area of a hemisphere and sphere and the volume of a sphere and hemisphere.

2. UDAYA COLLEGE OF
EDUCATION
UDAYA NAGER
AMMANDIVILAI

4. NAME
: A AMMU BITIYA
SUBJECT : MATHEMATICS
ROLL NO :

5. sphere

6. sphere
Definition:
A semicircle when revolved
about its diameter which is kept
fixed, a solid will be generated.
This solid is called a sphere.

7. examples of sphere
Some of the objects from our
daily life which brings to our mind the
concept of sphere is ball, globe,
lemon and shot put etc.

8. Diameter of the sphere
A line segment passing through the center
of the sphere and having its end points on the
sphere is called the diameter of the sphere.
A
O
B
AOB is the diameter

9. Center anD raDius of the sphere
The sphere is generated by one complete
revolution of the semi-circle AOB about the
diameter AOB. The center and radius of the
semi circle are the center and radius of the
sphere.

10. hemisphere
Definition:
A section of a sphere produced by
a plane is a circle. The circle, which passes
through the center of the sphere is the largest
circle.
It divides the sphere into two equal
parts. Each part is called hemisphere.

11. Illustration of surface area of
the hemisphere
The length of the string used to cover the
entire hemisphere is twice the length of the
string used to cover the circular region.

12. RemaRk
In case of sphere, the
curved surface area and the
total surface area are
same.
the

13. Volume of the spheRe
• Volume of the sphere
= 4/3 π r3 Cu. Units.

14. Volume of hemispheRe
Volume of hemisphere
=
½ × volume of sphere
=
½ × 4/3π r3
=
2/3π r3 Cu.units

15. Examples:1. Radius of the sphere is 4 m. Find its
surface area
Given : Surface area of the sphere
= 4 × πr 2
= 4 x π x 16
= 64 πm2

16. POST TEST
1. Define sphere?
2. What
is
the
surface
area
of
the
hemisphere?
3. What is the surface area of the sphere?

17. RESPONSES
1. A semicircle when revolved about its
diameter which is kept fixed, a solid will
be generated.
This solid is called a
sphere.
2. Surface area of the hemisphere = 2π r2 Sq.
units.
3. Surface area of the sphere = 4π r2 Sq. units.