Question

A soap bubble of radius r is blown up to form a bubble of radius 2r under isothermal conditions. If  is the surface tension of soap solution, the energy spent in doing so is  

Solution

Correct option is

 

Surface area of bubble of radius . Surface area of bubble of radius .

Therefore, increase in surface area . Since a bubble has two surfaces, the total increase in surface area 

SIMILAR QUESTIONS

Q1

A piece of copper having an internal cavity weights 264 g in air and 221 g in water. The density of copper is 8.8 gm–3. What is the volume of the cavity?

Q2

A stone of relative density k is released from rest on the surface of a lake. If viscous effects are ignored, the stone sinks in water with an acceleration of 

Q3

Two identical cylindrical vessels, each of base area A, have their bases at the same horizontal level. They contain a liquid of density . In one vessel the height of the liquid is h1 and in the other h2 > h1. When the two vessels are connected, the work done by gravity in equalizing the levels is

Q4

A cylindrical jar has radius r. To what height h should it be filled with a liquid so that the force exerted by the liquid on the sides of the jar equals the force exerted on the bottom?

Q5

A rectangular tank is filled to the brim with water. When a hole at its bottom is unplugged, the tank is emptied in time T. If the tank is half-filled with water, it will be emptied in time

Q6

Two capillary tubes A and B of radii ra and rb and lengths la and lbrespectively are held horizontally. The volume of water flowing per second through tube A is Qa when the pressure difference across its ends is maintained at P. When the same pressure difference is maintained across tube B, the volume of water flowing per second through it is Qb. The ratio  is 

Q7

. If a pressure difference P is maintained across tube A, the rate of flow of water in it is Q. If the tubes are connected in series and the same pressure difference P is maintained across the combination, the rate of flow through the combination will be

Q8

If the surface tension of soap solution is , What is the work done in blowing soap bubble of radius r?

Q9

The work done to break up a drop of a liquid of radius R and surface tension  into eight drops, all of the same size, is 

Q10

If the air bubble is formed at a depth h inside the container of soap solution of density , the total pressure inside the bubble is (here P0denotes the atmospheric pressure)