In a diffraction pattern due to single slit of width '$$a$$', the first minimum is observed at an angle of $$30^{\circ}$$ when the light of wavelength $$5400 \mathop A\limits^o$$ is incident on the slit. The first secondary maximum is observed at an angle of $$\left(\sin 30^{\circ}=\frac{1}{2}\right)$$

A stone is projected vertically upwards with speed '$$v$$'. Another stone of same mass is projected at an angle of $$60^{\circ}$$ with the vertical with the same speed '$$v$$'. The ratio of their potential energies at the highest points of their journey is $$\left[\sin 30^{\circ}=\cos 60^{\circ}=0.5, \cos 30^{\circ}=\sin 60^{\circ}=\frac{\sqrt{3}}{2}\right]$$

An electron (mass $$\mathrm{m}$$ ) is accelerated through a potential difference of '$$V$$' and then it enters in a magnetic field of induction '$$B$$' normal to the lines. The radius of the circular path is ($$\mathrm{e}=$$ electronic charge)

A capacitor, an inductor and an electric bulb are connected in series to an a.c. supply of variable frequency. As the frequency of the supply is increased gradually, then the electric bulb is found to