A soap bubble of radius a is blown so that its diameter is doubled. If T is the surface tension of water, the energy required to do this, at constant temperature is :

A soap bubble of radius a is blown so that its diameter is doubled. If

1.	A soap bubble of radius a is blown so that its diameter is doubled. If T is the surface tension of water, the energy required to do this, at constant temperature is :
Answer» 8`pia^(2)`T 12`pia^(2)`T 16`pia^(2)`T 24`pia^(2)`T Solution :Increase in area=`2[4pir2^(2)-4pir_(1)2]` Factor 2 is taken because soap bubble has 2 free SURFACES. `THEREFORE` Increase in area= 2`[4pi(2a)^(2)-4pia^(2)]` `=24pia^(2)` `therefore` Work done= surface tension `XX` Increase in area `=24pia^(2)T` Hence the correct choice is (d).

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A soap bubble of radius a is blown so that its diameter is doubled. If T is the surface tension of water, the energy required to do this, at constant temperature is :

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