NCERT Class 10 Maths Lab Manual – Surface Area of a Cylinder
Objective
To find the curved surface area and total surface area of a cylinder experimentally.
Prerequisite Knowledge
- Area of a rectangle.
- Area of a circle.
- Concept of surface area of a cylinder.
You can also download NCERT Maths Class 10 Solutions to help you to revise complete syllabus and score more marks in your examinations.
Materials Required
A white chart paper, a cylinder made of paper, a pair of scissors, a ruler, fevicol.
Procedure
- Remove the top and bottom circles of the cylinder.
- Make a vertical cut in the curved surface and lay the cylinder flat to get a rectangle as shown.
- Measure the length and breadth of the rectangle so formed.
Observation
- Top and bottom of cylinders are circles.
Therefore Area of 2 circles = \(\pi { r }^{ 2 }\), where r is the radius of base circle of cylinder - Length of rectangle = circumference of base of cylinder = \(2\pi \)r
- Breadth of rectangle = height = h
- Area of rectangle = \(\pi { r }\)x h = curved surface area of cylinder
- Total surface area of cylinder =\(2\Pi rh\) + \(\pi { r }^{ 2 }\)
= \(2\Pi r(h+r)\)
Result
Curved surface area of a cylinder = \(2\Pi rh\)
Total surface area of a cylinder = \(2\Pi r\) (h+r)
Learning Outcome
This activity’ clears the concept of curved surface area (lateral surface area) and total surface area of a cylinder.
Activity Time
Calculate the total surface area in terms of radius, where ‘tf represents the diameter of the cylinder.
Viva voice
Question 1:
What is curved surface area of a cylinder ?
Answer:
\(2\Pi rh\)
Question 2:
What is total surface area of a cylinder ?
Answer:
\(2\Pi r(r+h)\)
Question 3:
Write the number of circular faces of a cylinder ?
Answer:
2
Question 4:
What is the area of a circular face of cylinder ?
Answer:
\(\pi { r }^{ 2 }\)
Question 5:
If h = 7 cm and r=2 cm, find the lateral surface area of a cylinder.
Answer:
\(2\Pi rh\)=2× \(\frac { 22 }{ 7 } \) ×2×7= 88 cm3
Question 6:
What is the total area of circular faces of a cylinder ?
Answer:
\(2{\pi }{r}^{2}\)
Question 7:
What will be the curved surface area of a cylinder if its height is 3 times of its radius ?
Answer:
\(6{\pi }{ r }^{ 2}\)
Question 8:
What will be the curved surface area of a cylinder if its height is equal to the diameter of the base ? Answer:
\(4{\pi }{ r }^{2}\)
Multiple Choice Questions
Question 1:
The curved surface area of a right circular cylinder of height 14 cm is 88 cm2. The diameter of the base of
the cylinder is
(a) 2 cm
(b) 1 cm
(c) 1.5 cm
(d) none of these
Question 2:
The curved surface area of a right circular cylinder is 4.4 m2 . If the radius of the base of the cylinder is
0.7 m, find its height.
(a) 2 m
(b) 1.5 m
(c) 1 m
(d) none of these
Question 3:
A cylindrical pillar is 5 m in diameter and 3.5 m in height. Find the cost of painting the curved surface of the pillar at the rate of Rs.12.50 per m2
(d) Rs. 69.75
(b) Rs. 687.5
(c) Rs.67.75
(d) none of these
Question 4:
A rectangular sheet of paper 44 cm x 18 cm is rolled along its length and a cylinder is formed. The radius of the cylinder is
(a) 7 cm
(b) 9 cm
(c) 22 cm
(d) none of these
Question 5:
The radius and height of a cylinder are in the ratio 5 : 7 and its curved surface area is 220 cm2. The radius and height are respectively
(a) 5 cm and 7 cm
(b) 7 cm and 5 cm
(c) 5 cm and 5 cm
(d) 1 cm and 7 cm
Question 6:
The curved surface area of a cylinder is 1000 cm2 and its diameter is 20 cm. The height of the cylinder is
(a) 15.9 cm
(b) 15.8 cm
(c) 19.5 cm
(d) none of these
Question 7:
Find the curved surface area of a right circular cylinder of height 14 cm and base radius 1 cm.
(a) 88 cm2
(b) 80 cm2
(c) 82 cm2
(d) 84 cm2
Question 8:
What is the height of a cylinder of base radius as 1 cm and curved surface area as 88 cm2 ?
(a) 11 cm
(b) 14 cm
(c) 44 cm
(d) none of these
Question 9:
A metal pipe is 77 cm long. The inner diameter of a cross-section is 4 cm, the outer diameter being 4.4 cm. Its outer curved surface area is
(a) 1064.8 cm2
(b) 1406.8 cm2
(c) 1460.8 cm2
(d) none of these
Question 10:
What is the curved surface area of a right circular cylinder of base radius 0.7 m and height 1 m ?
(a) 4.4 m2
(b) 4.1 m2
(c) 1.1 m2
(d) none of these
Answers
1. (a)
2. (c)
3. (b)
4. (a)
5. (a)
6. (a)
7. (a)
8. (b)
9. (a)
10. (a)
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