Class 8 Chapter 16: Surface Area and Volume

Important Concepts and Formulas on Surface Area and Volume

1.      Amount of space occupied by a 3D object is called its volume.

2.      For a cuboid whose length is l units, breadth is b units and height is h units,

·        Volume of a cuboid = (l × b × h) cubic units

·        Total surface area of a cuboid = 2 (l × b + b × h + h × l) sq. units

·        Lateral surface area of a cuboid or area of four walls = 2 (l + b ) × h sq. units

·        The length of the diagonal of a cuboid = sqrt(l² + b² + h²) units

3.      For a cube of side a units,

            ·        Volume of a cube = a³ cubic units

            ·        Total surface area of a cube = 6a² sq. units

            ·        Lateral surface area of a cube = 4a² sq. units

            ·        Length of the diagonal of a cube = sqrt(3) × a units

4.      For a right circular cylinder of radius r units and height h units,

            ·        Volume of a cylinder = πr²h cubic units

            ·        Curved surface area of a cylinder = 2πrh sq. units

            ·        Total surface area of a cylinder = 2πr(r + h) sq. units

5.      For a hollow right circular cylinder of outer radius R units and inner radius r units,

            ·        Curved surface area = 2πh(R + r) sq. units

            ·        Total surface area = 2π(R + r) (h + R – r) sq. units

            ·        Volume = πh(R² – r² ) cubic units

6.      For a right circular cone of radius r units, height h units and slant height l units,

            ·        Volume of a cone = 1/3 πr²h cubic units

            ·        Curved surface area of a cone = πrl sq. units

            ·        Total surface area of a cone = πr(l + r) sq. units

7.      1 cm³ = 1 mL, 1000 cm³ = 1 L, 1000000 cm³ = 1 m³ = 1 kL.