A wire ' 1 ' $$\mathrm{cm}$$ long bent into a circular loop is placed perpendicular to the magnetic field of flux density '$$B^{\prime} W b \mathrm{~m}^{-2}$$. Within $$0.1 \mathrm{sec}$$, the loop is changed into a square of side '$$a$$' $$\mathrm{cm}$$ and flux density is doubled. The value of e.m.f. induced is
An iron piece of mass $$200 \mathrm{~g}$$ is kept inside a furnace for some time and then put in a calorimeter of water equivalent $$20 \mathrm{~g}$$ containing $$230 \mathrm{~g}$$ of water at $$20 \mathrm{C}$$. The steady state temperature attained by the mixture is $$60^{\circ}$$. The temperature of the furnace is (Specific heat capacity of iron is $$470 \mathrm{~J~kg}^{-1} \mathrm{C}^{-1}$$ )
A slit of width $$10 \times 10^{-7} \mathrm{~m}$$ is illuminated by light of wavelength $$500 \mathrm{~nm}$$. Angular position of the first minimum is
An ideal gas changes its state from $$\mathrm{A}$$ to $$\mathrm{C}$$ in two different paths $$\mathrm{ABC}$$ and $$\mathrm{AC}$$. The internal energy of the gas at state $$\mathrm{C}$$ is $$20 \mathrm{~J}$$ and at state $$\mathrm{B}$$ is $$10 \mathrm{~J}$$. Heat supplied to the gas to go from $$\mathrm{B} \rightarrow \mathrm{C}$$ is