Question

A ring is cut from a platinum tube 8.5 cm internal and 8.7 cm
external diameter. It is supported horizontally from the pan
of a balance, so that it comes in contact with the water in a
glass vessel. If an extra 3.97. If is required to pull it away
from water, the surface tension of water is
(a) 72 dyne cm⁻¹ (b) 70.80 dyne cm⁻¹
(c) 63.35 dyne cm⁻¹ (d) 60 dyne cm⁻¹

Answer 1

Answer:

A ring is cut from a platinum tube 8.5cm8.5cm internal and 8.7cm8.7cm external diameter. It is supported horizontally from the pan of a balance, so that it comes in contact with the water in a glass vessel. If an extra 3.103gf3.103gf is required to pull it away from water, the surface tension of water is

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Text Solution

Answer 2

Explanation:

2πr

1

+2πr

2

)σ=mg

[2πx

2

8.7

+2πx

2

8.5

]σ=3.97x980

⇒σ=72dynecm

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