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$12.11 In Bohrs atomic model of hydrogen atom the electron is in an orbit around the nuclear proton at a distance of 5.29 \times 10^{-11} " \mathrm{m} with a speed of 2.18 \times 10^{6} \mathrm{~ms}^{-1} . \left(e=1.60 \times 10^{-10} \mathrm{C}\right. mass of electron \left.=9.10 \times 10^{-31} \mathrm{~kg}\right) . Find(c) The ionization energy for the atom in eV$

$13.19. What are hazards of staticelectricity?$

$The electric flux through the surface of a sphere having a point charge at its centre depends upon:A) Surface area of sphereB) Radius of sphereC) Quantity of charge inside the sphereD) None of these$

$An electric field is most directly related to:A) The momentum of a test chargeB) The kinetic energy of a test chargeC) The potential energy of a test chargeD) The force acting on a test charge$

$13.4. What is gold leaf electroscope? Discuss its working principle with a labelled diagram.$

$Three capacitors of capacitance 2 \mu \mathrm{F} each are connected in parallel. Their equivalent capacitance will be:A) 0.66 \mu \mathrm{F} B) 4 \mu \mathrm{F} C) 6 \mu \mathrm{F} D) 1.5 \mu \mathrm{F}$

$The force experience by a charge 10 \mu \mathrm{C} when placed at a point is 10^{-5} \mathrm{~N} . the electric field intensity at the point is:A) 0.1 \mathrm{NC}^{-1} B) 1 \mathrm{NC} C) 10 \mathrm{NC}^{-1} D) 1 \mathrm{NC}^{-1}$