# Sphere formula

## Sphere formula

A perfectly symmetrical 3 – Dimensional circular shaped object is a Sphere. The line that connects from the center to the boundary is called radius of the square. You will find a point equidistant from any point on the surface of a sphere. The longest straight line that passes through the center of the sphere is called the diameter of the sphere. It is twice the length of the radius of the sphere.

$\large Diameter\;of\;a\;sphere=2r$

$\large Circumference\;of\;a\;sphere=2\pi r$

$\large Surface\;area\;of\;a\;sphere=4\pi r^{2}$

$\large Volume;of\;a\;sphere=\frac{4}{3}\: \pi r^{3}$

### Solved Example

Question: Calculate the diameter, circumference, surface area and volume of a sphere of radius 9 cm ?

Solution:

Given,
r = 7 cm

Diameter of a sphere
=2r
= 2 × 9
=18 cm

Circumference of a sphere

= 2πr
= 2 × π × 9
= 56.54 cm

Surface area of a sphere

$4\pi r^{2}$
$4\times \pi \times 9^{2}$
$4\times \pi \times 81$
= 1017.87 cm

Volume of a sphere

$\frac{4}{3}\;\pi r^{3}$
$\frac{4}{3}\;\pi 9^{3}$
= 338.2722 cm

 More topics in Sphere Formula Volume of a Sphere Formula Surface Area of a Sphere Formula

#### Practise This Question

In each of the following question, an Assertion (A) is followed by a corresponding Reason (R). Use the following keys to choose the appropriate answer:

Assertion (A): There is a natural asymmetry between converting work to heat and converting heat to work.
Reason (R): No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work.