Question

09.
Two spherical balls of the same radius carry charges - 0.4 C and -0.9 C. Calculate the number of
electrons to be transferred from one ball to another such that they attain the same charge.
Calculate the charge in mass of an object if 800 electrons are given to it, Given : Mass of an electron
is 9.1 x 10-31 kg.
​

Answer 1

Question 1:

Two spherical balls of the same radius carry charges - 0.4 C and -0.9 C. Calculate the number of electrons to be transferred from one ball to another such that they attain the same charge.

Solution:

Average charge of the sphere

$= \dfrac{ - 0.4 + ( - 0.9)}{2}$

$= \dfrac{ - 0.4 - 0.9}{2}$

$= \dfrac{ - 1.3}{2}$

$= -0.65 \: C$

So, -0.4 C will gain -0.25 C charge and -0.9 C will lose equivalent amount of charge.

So, electrons transferred :

$no. \: of \: {e}^{ - } = \dfrac{ - 0.25}{ - 1.6 \times {10}^{ - 19} }$

$\boxed{ = > no. \: of \: {e}^{ - } = 0.15625 \times {10}^{19} }$

Question 2:

Calculate the charge in mass of an object if 800 electrons are given to it.

Solution:

The object will gain a mass of :

$= 800 \times (9.1 \times {10}^{ - 31} )$

$= 8 \times 9.1 \times {10}^{ - 29}$

$\boxed{ =72.8 \times {10}^{ - 29} \: kg}$

HOPE IT HELPS.