A big drop of radius R is formed by 1000 small droplets of water, then the radius of small drop is
(1) R/2
(2) R/5
(3) R/6
(4) R/10
8000 identical water drops are combined to form a big drop. Then the ratio of the final surface energy to the initial surface energy of all the drops together is
(1) 1 : 10
(2) 1 : 15
(3) 1 : 20
(4) 1 : 25
When two small bubbles join to form a bigger one, energy is
(1) Released
(2) Absorbed
(3) Both (1) and (2)
(4) None of these
A water film is formed between the two straight parallel wires, each of length \(10~\text{cm}\), kept at a separation of \(0.5~\text{cm}.\)Now, the separation between them is increased by \(1~\text{mm}\) without breaking the water film. The work done for this is
(surface tension of water =\(7.2\times 10^{-2}~\text{N/m}\))
1. \(7.22\times 10^{-6}~\text{J}\)
2. \(1.44\times 10^{-5}~\text{J}\)
3. \(2.88\times 10^{-5}~\text{J}\)
4. \(5.76\times 10^{-5}~\text{J}\)
A drop of mercury of radius 2 mm is split into 8 identical droplets. Find the increase in surface energy. (Surface tension of mercury is )
(1)
(2)
(3)
(4)
If two soap bubbles of equal radii r coalesce then the radius of curvature of interface between two bubbles will be
(1) r
(2) 0
(3) Infinity
(4) 1/2r
The angle of contact between glass and mercury is
(1) 0°
(2) 30°
(3) 90°
(4) 135°
A mercury drop does not spread on a glass plate because the angle of contact between glass and mercury is
(1) Acute
(2) Obtuse
(3) Zero
(4)
The liquid meniscus in the capillary tube will be convex if the angle of contact is
(1) Greater than 90°
(2) Less than 90°
(3) Equal to 90°
(4) Equal to 0°
The value of contact angle for kerosene with a solid surface.
(1) 0°
(2) 90°
(3) 45°
(4) 33°