While doing his experiment, Millikan one day observed the following charges on a single drop

$(i)$ $6.563 \times {10^{ - 19}}C$       $  (ii)$ $8.204 \times {10^{ - 19}}C$

$(iii)$ $11.50 \times {10^{ - 19}}C$       $ (iv)$ $13.13 \times {10^{ - 19}}C$

$(v)$ $16.48 \times {10^{ - 19}}C$       $ (vi)$ $18.09 \times {10^{ - 19}}C$

From this data the value of the elementary charge $(e)$ was found to be

When electron beam passes through an electric field, they gain kinetic energy. If the same beam passes through magnetic field, then

The specific charge of an electron is

In a Thomson set-up for the determination of e/m, electrons accelerated by $2.5$ $kV$ enter the region of crossed electric and magnetic fields of strengths $3.6 \times {10^4}V{m^{ - 1}}$ and $1.2 \times {10^{ - 3}}T$ respectively and go through undeflected. The measured value of $e/m$ of the electron is equal to

An oxide coated filament is useful in vacuum tubes because essentially

If an electron oscillates at a frequency of $ 1 GHz$  it gives