In Fraunhofer diffraction pattern, slit width is 0.3 mm and screen is at 1.5 m away from the lens. If wavelength of light used is $4500 \mathop {\rm{A}}\limits^{\rm{o}}$, then the distance between the first minimum on either side of the central maximum is [ $\theta$ is small and measured in radian.]

Two boys are standing at points A and B on ground, where distance $\mathrm{AB}=\mathrm{x}$. The boy at B stars running perpendicular to $A B$ with velocity $\mathrm{v}_1$. The boy at A starts running simultaneously with velocity v and meets the other boy in time $t$. The value of $t$ is

The temperature of an ideal gas is increased from 100 K to 400 K . If ' $x$ ' is the root mean square velocity of its molecules at 100 K , r.m.s. velocity becomes

Current $I$ is carried in a wire of length ' $L$ '. If wire is bent into a circular coil of single turn, the maximum torque in a given magnetic field $B$ is