[Use pi = 3.14]
ANSWER:
Given: 3.90 - 4.10
Answer calculated: 3.95 nm
Steps:
1. 25 nm wraps once = it covers the perimeter of a 'circle that coincides with the sphere's diameter'
Thus, 25 nm = perimeter = 2r(pi) or pi x D,
2. Perimeter is pi x D = 25
Therefore,
D = 25 / 3.14
D = 7.9 nm
3. Find the radius from D like a school child :)
because D = 2R
Therefore, R = D/2 = 7.9 nm / 2 = 3.95 nm
R = 3.95 nm.
My answer matches with the answer key, so I think this does well to the question.
If I am wrong, do let me know in the comments below.
You can also let me know what other GATE BT / XL or CSIR - LS you'd like to see me solve!
Byee.
