Calculate the voltage needed to balance an oil drop carrying 10 electrons, when located between plates of a capacitor, which are 5 mm apart. Given, mass of the drop `= 3xx 10^-16 kg`, charge on electrno `= 1.6 xx 10^-19 C and g = 9.8 m s^-2`

Calculate the magnitude and direction of the electric field. Which keeps a proton just floating. Give that mass of proton 1.67 xx 10^-27 kg, charge on proton = 1.6 xx 10^-19 C and g = 9.8 ms^-2

Obtain de-Broglie waveelngth of an electon of kinetic energy 150 eV.Given mass of electron, m=9.1 xx 10^(-31) kg ,charge on electron, e=1.6 xx 10^(-19) C and Planck's constant , h=6.62 xx 10^(-34) J s .

Calculate the magnitude of the electrostatic force exerted by the proton on the electron in the hydrogen atom and compare it with the weight of the electron. Given that mass of electron is 9.1 xx 10^-31 kg, charge on electron is 1.6 xx 10^-19 C and radius of hydrogen atom is 0.53 overset(@)A .

Calculate the ratio of electrostatic to gravitational force between two electrons placed at a certain distance in air. Given that m_e = 9.1 xx 10^31 kg, e = 1.6 xx 10^19C and G = 6.6 xx 10^17 N m^2 kg^-2

Calculate the mass of the earth. Given radius of the earth =6.4xx10^-6 m and g = 9.8 m//s^2

A spherical oil drop of raiuds 10^-4 cm has on it at a certain time a charge of 40 electrons. Calculate the energy that would be required to place an additional electron on the drop. Charge on a electron =1.6 xx 10^-19 C

If the free electron density of copper is 8.6xx10^(28)m^(-3) and resistivity of copper at room temperature is 1.7xx10^(-6)Omega cm , find the relaxation time for the free electrons of copper. Given, mass of electron =9.1xx10^(-31) kg , and charge of electron =1.6xx10^(-19)C. Boltzmann's constant k = 1.38 xx 10^-23 J K^-1