The work function of a substance is $$3.0 \mathrm{~eV}$$. The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately;

Primary coil of a transformer is connected to $$220 \mathrm{~V}$$ ac. Primary and secondary turns of the transforms are 100 and 10 respectively. Secondary coil of transformer is connected to two series resistances shown in figure. The output voltage $$\left(V_0\right)$$ is :

A particle of mass $$\mathrm{m}$$ is projected with a velocity '$$\mathrm{u}$$' making an angle of $$30^{\circ}$$ with the horizontal. The magnitude of angular momentum of the projectile about the point of projection when the particle is at its maximum height $$\mathrm{h}$$ is :

The diffraction pattern of a light of wavelength $$400 \mathrm{~nm}$$ diffracting from a slit of width $$0.2 \mathrm{~mm}$$ is focused on the focal plane of a convex lens of focal length $$100 \mathrm{~cm}$$. The width of the $$1^{\text {st }}$$ secondary maxima will be :