The latent heat of vaporisation of water is $$2240 \mathrm{~J}$$. If the work done in the process of vaporisation of $$1 \mathrm{~g}$$ is $$168 \mathrm{~J}$$, the increase in internal energy is
A particle of mass $$2 \mathrm{mg}$$ has the same wavelength as a neutron moving with a velocity of $$3 \times 10^5 \mathrm{~ms}^{-1}$$. The velocity of the particle is (mass of neutron is $$1.67 \times 10^{-27} \mathrm{Kg}$$)
Two narrow parallel slits illuminated by a coherent monochromatic light produces an interference pattern on a screen placed at a distance $$\mathrm{D}$$ from the slits. The separation between the dark lines of the interference pattern can be increased by
Three point charges are located on a circular arc at $$\mathrm{A}, \mathrm{B}$$ and $$\mathrm{C}$$ as shown in the figure below. The total electric field at the centre of the $$\operatorname{arc}(\mathrm{C})$$ is