The frequency f of the note produced by a string can be increased by :

1. decreasing the length l of the string
2. decreasing the radius r of the string
3. increasing the tension T of the string
4. All of these

If l is the length of the string stretched between its ends, the wavelength of different modes in Figure (1), (2) and (3) will be :

1. 2l/2, 2l, 2l/3
2. 2l/3, 2l/2, 2l
3. 2l, 2l/2, 2l/3
4. 2l, 21/3, 2l/2

A slim branch of a tree is pulled and released. It makes …………… vibrations.

1. damped
2. natural
3. forced
4. resonant

A body is vibrating under the influence of an external periodic force of frequency exactly equal to the natural frequency of the vibrations of the body. It executes :

1. damped vibrations
2. forced vibrations
3. resonant vibrations
4. natural vibrations