A soap bubble of radius \(r\) is blown up to form a bubble of radius \(2r\) under isothermal conditions. If \(T\) is the surface tension of the soap solution, the energy spent in the blowing is:
1. \(3\pi Tr^2\)
2. \(6\pi Tr^2\)
3. \(12\pi Tr^2\)
4. \(24\pi Tr^2\)
A current of \(1.6\) A is passed through a solution of CuSO4. How many Cu++ ions are liberated in one minute? (Electronic charge= \(1.6\times10^{-19}\) C)
1. 3 × 1020
2. 3 × 1010
3. 6 × 1020
4. 6 × 1010
1. | a magnet |
2. | an unmagnetised iron bar |
3. | a moving charge |
4. | stationary charge |
1. | they travel with the speed of sound. |
2. | the frequency is not constant. |
3. | they can, heavily absorbed by the atmosphere. |
4. | the height of antenna has to be increased several times. |
A | B | Y |
0 | 0 | 1 |
0 | 1 | 1 |
1 | 0 | 1 |
1 | 1 | 0 |
1. \(0.01\) m
2. \(0.02\) m
3. \(0.05\) m
4. \(0.03\) m