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Question Id:  PH0000008 Question: Explain the meaning of the statement ‘electric charge of a body is quantised'. Answer : Charge( may be positive or negative) of any body is integral multiple of electronic charge. This phenomena is quantisation of charge. If a body has \(Q\) amount of charge then it can be say from the quantisation of charge that \(Q=\pm ne\) where \(e\) is electronic charge [ \(e=-1.6 \times 10^{-19}C\) ] and \(n=1,2,3,4,......\) Fig-1: Quantisation of charge Explanation : A body get charged in two way By losing some electron By gaining some electrons An atom has equal number of proton and electron due to ths fact in general an atom is neutral but w hen a body lose some electron then it become positively charged in this case number of proton is more in the atom and when gain some electron it become negatively charged as in this case number of electron is more in the atom. As fraction number of electron can not be transferred (lose or gain) so it means a bod...

Question Id:  PH0000007 Question :   Four point charges qA = 2 µC, qB = –5 µC, qC = 2 µC, and qD = –5 µC are located at the corners of a square ABCD of side 10 cm. What is the force on a charge of 1 µC placed at the centre of the square? Answer : zero  Explanation :  According to the given question you can draw the figure look like as given below.   Fig-1: Coulomb's Force at the centre of square Let, side of the square is a unit. Then length of the corner is \(a\sqrt{2}\) . So, the distance froom centre to corner is \(\frac{a}{\sqrt{2}}\) . Given \(2\mu C\) charge will apply foce towards the centre. For both the \(2\mu C\) the applied forces on \(1\mu C\) chrge are equal and opposite to each other. And value of the force is  \(F=\frac{1}{4 \pi \epsilon_0} \times \frac{1 \times 2}{(\frac{a}{\sqrt 2})^{2}} \mu N\) \[\Rightarrow F=\frac{1}{4 \pi \epsilon_0} \times \frac{4}{a^{2}} \mu N\] As the force are opposite and equal so  the resultant...