Introduction
The main Difference between circle and sphere is that a circle is a two-dimensional figure whereas, a sphere is a three-dimensional object. A circle has an area that can be calculated with the formula (πr²), a sphere along along with an area calculated with the formula (4πr²). All of the points on a circle are equally spaced apart from the center along a plane whereas all the points on a sphere are equally spaced apart from the center along any axes.
Table of Contents
What is Circle?
A circle is defined as a 2D figure, which is round in shape. It is characterized by its radius, which is the distance from the center to any point on the circle, or its diameter, which is the distance across the circle passing through the center. Examples of Circle– Wheels, Ring and Pizza etc.
Properties of Circle
- A circle is a closed 2D shape that has one curved face.
- The diameter of a circle is the longest chord of a circle.
- A circle has an area and a circumference as its boundary.
- The diameter of a circle is double the radius.
Formulas Related to Circle
- Diameter of a Circle= 2 × Radius
- Radius of a Circle= Diameter/2
- Circumference of a Circle= 2πr
- Area of a Circle= πr²
What is Sphere?
A sphere is a three-dimensional round-shaped object. A sphere has an area and a volume instead of a circumference. A sphere is the set of points that are all at the same distance from a given point. Examples of Sphere- Football, Basketball, Marble and The Sun etc.
Properties of Sphere
- A sphere is a 3D shape that has one curved face.
- The diameter is the longest straight line that passes through the center of the sphere.
- A sphere has an area and a volume instead of a circumference.
- Spheres have perfect symmetry around their centers.
Types of Sphere
- Solid Sphere: A solid sphere is a three-dimensional object where the entire interior space is filled with a homogeneous material.
- Hollow Sphere: A hollow sphere is a three-dimensional shape that has a spherical outer surface but contains an empty space or cavity inside.
Formulas Related to Sphere
- Diameter of a Sphere= 2 × Radius
- Surface Area of Sphere= 4πr²
- Volume of a Sphere= 4/3πr³
Similarities between Circle and Sphere
Circles and spheres share several similarities due to their geometric properties:
- Shape: Both circle and sphere are geometric shapes with a symmetrical round form.
- Center: They both have a center point from which all points on their surfaces are equidistant.
- Radii: Both shapes have radii, which are the distances from their centers to any point on their surfaces.
- Diameter: Circles and spheres have diameters, which are twice the length of their radii.
Difference between Circle and Sphere
The main difference between circle and sphere are as follows:
| Feature | Circle | Sphere |
| Definition | A circle is a flat, round shape with all points on its circumference equidistant from its center point. | A sphere is a round, 3-dimensional object where all points on its surface are equidistant from its center. |
| Dimension | Circle is a two-dimensional figure. | Sphere is a three-dimensional figure. |
| Examples | Coin, clock face, pizza | Ball, planet, sun |
| Shape | Flat shape with a circumference. | Round shape with a surface area. |
| Circumference | Circumference of a Circle- 2πr | A sphere does not have the circumference. |
| Area | Area of Circle- πr² | Surface area of Sphere- 4πr² |
| Volume | There is no volume. | Volume of Sphere- 4/3πr³ |
| Equations | The standard equation of a circle: (x-h)² + (y-k)² = r² | The standard equation of a sphere: (x-h²) + (y-k²)+ (z-l)²= r² |
| Application | Used in planar geometry, engineering. | Used in three-dimensional geometry. |
Summary
A circle is a 2-dimensional shape consisting of all points equidistant from a center point, forming a flat shape with a circumference. It’s commonly seen in objects like coins or clock faces.
On the other hand, a sphere is a 3-dimensional shape consisting of all points equidistant from a center point, forming a round shape with a surface area. Real-world examples include balls, globes, and planets like earth.
Solved Examples
Q.1 What is the circumference of a circle, whose radius is 5 m?
Solution: Given, radius of circle= 5m
Therefore, Circumference of circle= 2πr = 2× π× 5 = 10π m.
Q.2 What is the area of a wheel, whose radius is 4 cm?
Solution: Given, radius of circle = 4 cm
Therefore, area of circle= πr² = π× 4²= 16π sq. cm.
Q.3 What is the surface area of a sphere, whose radius is 7 cm?
Solution: Given, radius of sphere= 7 cm
Therefore, surface area of sphere= 4πr² = 4× π ×7² = 4 ×49 π = 196 sq. cm.
Q.4 What is the volume of a sphere, whose radius is 9 cm?
Solution: Given, radius of sphere= 9 cm
Therefore, volume of sphere= 4/3 πr³ = 4/3 ×π ×9³ = 4/3× 729× π =972π cm³
Things to Remember
- The value of π = 22/7 or 3.14
- The perimeter of circle= The circumference of circle.
- A circle does not have volume.
- A sphere does not have circumference.
Practice Questions
- What is Circle?
- What is Sphere?
- What is diameter?
- What is radius?
- What is the volume of a sphere, whose radius is 7 m?
- What is the area of a circle, whose radius is 5 cm?
Recommended Reading
All Formulas of Mensuration Class 8
FAQs
Q.1 What is the volume of a circle?
Answer- A circle does not have volume, because it has only length and breadth.
Q.2 Are both circle and sphere same?
Answer- No, a circle and a sphere are not the same. A circle is a two-dimensional shape consisting of all points in a plane that are a fixed distance from a given point, called the center. On the other hand, a sphere is a three-dimensional shape defined as the set of all points in space that are a fixed distance (the radius) from a given point(center).
Q.3 What is hemisphere?
Answer- A hemisphere is half of a sphere, which is a three-dimensional round object like a ball. It’s divided into two equal parts by a plane passing through its center.
Q.4 What is chord of a circle?
Answer- A chord of a circle is a straight line segment connecting two points on the circle’s circumference.
Q.5 What is the difference between circle and sphere?
Answer- The main difference between circle and sphere is a circle is a 2D shape, while a sphere is a 3D shape.
Q.6 What is the similarities of circle and sphere?
Answer- Circle and sphere both are geometric shape, they both have a center point from which all points on their surfaces are equidistant.