On superposition of two waves \(y_{1}=3\sin\left ( \omega t-kx \right )\) and \(y_{2}=4\sin\left ( \omega t-kx+\frac{\pi }{2} \right )\) at a point, the amplitude of the resulting wave will be:
1. \(7\)
2. \(5\)
3. \(\sqrt{7}\)
4. \(6.5\)

Five identical polaroids are placed coaxially with \(45^{\circ}\) angular separation between pass axes of adjacent polaroids as shown in the figure. (\(I_0\): Intensity of unpolarized light)
          
The intensity of light, \(I\), emerging out of the \(5\)^th polaroid is:

Two light sources are said to be coherent when their:

Two coherent sources are \(0.3~\text{mm}\) apart. They are \(1~\text{m}\) away from the screen. The second dark fringe is at a distance of \(0.3~\text{cm}\)  from the center. The distance of the fourth bright fringe from the centre is:
1. \(0.6~\text{cm}\)
2. \(0.8~\text{cm}\)
3. \(1.2~\text{cm}\)
4. \(0.12~\text{cm}\)

Huygens' wave theory allows us to know the:

Unpolarized light of intensity \(32\) Wm^–2 passes through three polarizers such that the transmission axes of the first and second polarizer make an angle of \(30^{\circ}\) with each other and the transmission axis of the last polarizer is crossed with that of the first. The intensity of the final emerging light will be:
1. \(32\) Wm^–2
2. \(3\) Wm^–2
3. \(8\) Wm^–2
4. \(4\) Wm^–2