An oil drop of 12 excess electrons is held stationary under a constant electric field of `2.55 xx 10^4 NC^-`1 in Millikan’s oil drop experiment. The density of the oil is `1.26 g cm^-3`. Estimate the radius of the drop. `(g = 9.81 m s^-2, e = 1.60 xx 10^-19 C)`.

In a chamber, a uniform magnetic field of 6.5 G (1 G = 10^-4 T) is maintained. An electron is shot into the field with a speed of 4.8 xx 10^6 m s^-1 normal to the field. Explain why the path of the electron is a circle. Determine the radius of the circular orbit. (e = 1.5 xx 10^-19 C. m_e= 9.1x10^-31 kg)

An electric dipole, when held at 30^@ with respect to a uniform electrc field of 3 xx 10^4 N C^-1 experienes a troque of 27xx10^25N m . Calculate dipole moment of the dipole.

Find the flux density of the magnetic field to cause 62.5 eV electron to move in a circular path of radius 5 cm. Given m = 9.1 xx 10^-31 kg, e = 1.6 xx 10^-19 C

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

An electric dipole, when held at 30^@ with respect to a uniform electrc field of 10^4 N C^-1 experienes a troque of 9xx10^25N m . Calculate dipole moment of the dipole.

An electric diple is placed at angle of 60^@ with an electric field of strength 4xx10^5NC^-1 . It experiences a torque equal to 8sqrt3xx10^-5 Nm. Calculate the charge on the dipole, if dipole is of length 4 cm.

Quarks inside protons and neutrons are thought to carry fractional charges (+2/3e, -1/3e) .Why do they not show up in Millikan's oil drop experiment?

An infinite line charge produces a field of 9xx 10^4 NC^-1 at a distance of 4 cm. Calcualte the linear charge density.

Electrons move at right angles to a magnetic field of 100 gauss and enter it with a velocity fo 2xx10^10 cms^-1 . Find the radius of their circular path. Given e//m = 1.7 xx 10^7 e.m.u g^-1