Book Online Demo

Check Your IQ

Try Test

Courses

Offline Centres

A hollow cylinder of negligible thickness and radius $r$ is mounted by a hollow hemisphere of the same radius. The height of the cylinder is $h$ . If the solid formed is to be painted . What is the total surface area that has to be painted?

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

2 πr h + 4 π r^{2}

2 πr h + π r^{2}

2 πr h + 3 π r^{2}

None of the above

answer is C.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Given,
A hollow cylinder of radius

r

.
The height of the cylinder is

h

Total surface area painted to be

=

curved surface area of cylinder

+

curved surface area of hemisphere

+

area of base circle of cylinder

A = 2 πr h + 2 π r^{2} + π r^{2}

\Rightarrow A = 2 πr h + 3 π r^{2}

Therefore, the total surface area that has to be painted is

2 πr h + 3 π r^{2}

.
Hence, the correct option is 3.

JEE

NEET

Foundation JEE

Foundation NEET

CBSE