Light of wavelength $$5000 \mathop A\limits^o$$ is incident normally on a slit. The first minimum of the diffraction pattern is observed to lie at a distance of $$5 \mathrm{~mm}$$ from the central maximum on a screen placed at a distance of $$2 \mathrm{~m}$$ from the slit. The width of the slit is

When two tuning forks are sounded together, 5 beats per second are heard. One of the forks is in unison with $$0.97 \mathrm{~m}$$ length of sonometer wire and the other is in unison with $$0.96 \mathrm{~m}$$ length of the same wire. The frequencies of the two tuning forks are

The work done in rotating a dipole placed parallel to the electric field through $$180^{\circ}$$ is W. So, the work done in rotating it through $$60^{\circ}$$ is $$\left(\cos 0^{\circ}=1, \cos 60^{\circ}=\frac{1}{2}, \cos 180^{\circ}=-1\right)$$

When an electron is excited from its 4 th orbit to 5 th stationary orbit, the change in the angular momentum of electron is approximately.

(Planck's constant $$=h=6.63 \times 10^{-34} \mathrm{~J}-\mathrm{s}$$ )