Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the beams is $$\pi / 2$$ at point $$\mathrm{A}$$ and $$\pi$$ at point $$\mathrm{B}$$. Then the difference between the resultant intensities at $$\mathrm{A}$$ and $$\mathrm{B}$$ is

A body is executing S.H.M. under the action of force having maximum magntude $$50 \mathrm{~N}$$. When its energy is half kinetic and half potential; the magnitude of the force acting on the particle is

The peak value of an alternating emf '$$\mathrm{e}$$' given by $$\mathrm{e}=\mathrm{e}_0 \cos \omega \mathrm{t}$$ is 10 volt and its frequency is $$50 \mathrm{~Hz}$$. At time $$\mathrm{t}=\frac{1}{600} \mathrm{~s}$$, the instantaneous e.m.f is $$\left(\cos \frac{\pi}{6}=\sin \frac{\pi}{3}=\frac{\sqrt{3}}{2}\right)$$

The wavelength of sound in any gas depends upon