A block of mass 2 kg is pushed against a rough vertical wall with a force of 40 N, coefficient of static friction being 0.5. Another horizontal force of 15 N, is applied on the block in a direction parallel to the wall. If the block will move, then its direction would be:

1.  15 ° with 15 N force

2.  53 ° with 15 N force

3.  45 ° with 15 N force

4.  75 ° with 15 N force

A square loop is made by a uniform conductor wire as shown in the figure,     
The net magnetic field at the centre of the loop if the side length of the square is a:
1. \(\frac{\mu_{_0}i}{2a}\)
2. zero
3. \(\frac{\mu_{_0}i^2}{a^2}\)
4. None of these

The electron of an H-atom is revolving around the nucleus in circular orbit having radius \(\frac{h^2}{4\pi me^2}\) with \(\Big(\frac{2\pi e^2}{h}\Big).\) The current produced due to the motion of the electron is:
1. \(\frac{2\pi m^2e^2}{3h^2}\)
2. zero
3. \(\frac{2\pi^2me}{h^2}\)
4. \(\frac{4\pi^2me^5}{h^3}\)

Two small balls, each carrying a charge \(q\) are suspended by equal insulator strings of length 1 m from the hook of a stand. This arrangement is carried in a satellite in space. The tension in each string will be:
1. \(\frac{1}{4\pi \varepsilon_0}\frac{q}{I^2}\)
2. \(\frac{1}{4\pi\varepsilon_0}\frac{q^2}{4I^2}\)
3. \(\frac{1}{4\pi\varepsilon_0}\frac{q^2}{I^2}\)
4. \(\frac{1}{(4\pi~\varepsilon_0)}\frac{q}{I}\)

A vessel of depth \(t\) is half filled with a liquid having a refractive index \(n_1\) and the other half is filled with water having a refractive index \(n_2.\) The apparent depth of the vessel as viewed from the top is:
1. \(\frac{2t(n_1+n_2)}{n_1n_2}\)
2. \(\frac{tn_1n_2}{(n_1+n_2)}\)
3. \(\frac{t(n_1+n_2)}{2n_1n_2}\)
4. \(\frac{n_1n_2}{(n_1+n_2)t}\)