Question

a polythene peace is rubbed with wool and it has been found to acquire a negative charge of 3×10-7 coulomb
(a) how many electron have transferred from wool to polythene?
(a) is there a transfer of mass from wool to polythene? if yes how much? ​

Answer 1

Answer: (a) When polythene is rubbed against wool, a number of electrons get transferred from wool to polythene. Hence, wool becomes positively charged and polythene becomes negatively charged.

Amount of charge on the polythene piece, q = −3 × 10−7 C

Amount of charge on an electron, e = −1.6 × 10−19 C

Number of electrons transferred from wool to polythene = n

n can be calculated using the relation, q = ne

n equals q over e

=fraction numerator minus 3 x 10 to the power of minus 7 end exponent over denominator minus 1.6 x 10 to the power of minus 19 end exponent end fraction

= 1.87 × 1012

Therefore, the number of electrons transferred from wool to polythene is 1.87 × 1012.

(b) Yes. There is a transfer of mass occur. This is because an electron has mass,

as we know

me = 9.1 × 10−3 kg

Total mass transferred from wool to polythene,

m = me × n

= 9.1 × 10−31 × 1.85 × 1012

= 1.706 × 10−18 kg

Hence, a negligible amount of mass is transferred from wool to polythene.