PHY2D_Quiz4

# PHY2D_Quiz4 - over a vertical distance of 0.6 cm With the...

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QUIZ 4 PHYSICS 2D SPRING QUARTER 2009 Professor S.K.Sinha Formulas and constants Mass of electron = 9.1. 10 -31 kg Charge on electron = 1.6.10 -19 C Planck’s Constant h= 6.626. 10 -34 J.s =4.136. 10 -15 eV.s h = h / 2 ! = 1.055.10 " 34 J . s = 6.582.10 " 16 eV . s 1 eV =1.6. 10 -19 J Coulomb’s constant k = 1/ (4 !" 0 ) = 8.99.10 9 N . m 2 / kg 2 Velocity of light c = 3.10 8 m/s Bohr’s quantization for Angular momentum mvr = n h Bohr radius a 0 =0.529. 10 -10 m 1 Rydberg (Energy required to ionize hydrogen atom) =13.6 eV Rydberg Constant R = 1.097. 10 7 m -1 Energy of photon E = hf For photon λ f = c Force due to Electric field : F = q E Force due to Magnetic Field: F = q vxB Drag Force on drop of radius α and velocity ν in medium of viscosity η (always opposite to direction of v) : D = 6 !"# v = Cv 1. In an oil-drop experiment such as Millikan’s the droplets are studied

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Unformatted text preview: over a vertical distance of 0.6 cm. With the electric field (directed downwards) off, a droplet is observed to fall over this distance in a time of 21.0 s. With the electric field turned on, the droplet is observed to rise with constant velocity. Over time, this velocity varies discontinuously. The following two rise times were measured: 46.0 s and 15.5 s. Deduce the ratios of the charges on the droplet corresponding to these two rise times and show that it is the ratio of two small integers. 10 pts. 2. (a)Using the Bohr theory of the atom, calculate the wavelength in meters of the photon emitted when a helium atom (Z =2) makes a transition from the state n=3 to the state n=2. (b)What is the radius of the n=2 orbit in meters ?...
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PHY2D_Quiz4 - over a vertical distance of 0.6 cm With the...

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