A question on Gauss's law

Question : A spherical liquid drop of radius r has charge q. If n number of such drops coalesces to form a single bigger drop , then on the surface of bigger drop what is
(1) charge
(2) charge density
(3) electric field and
(4) potential

This question is quite a easy one try and solve it though I'll provide the solution of this question.
For solution visit this link

Subjective Question Archive

Hi all,
I have given the link of most of the subjective questions in this blog under the tab "Subjective Question Archive" please visit the page and i hope you will definitely learn something or the other about solving questions in various topics in physics while going through these questions. Most of the questions given came along with their answers and solutions .
Hope you like the page
With best wishes for your exams
Physics Expert

Advantages an disadvantages of A.C. over D.C.

  1. The generation of A.C. is cheaper than that of D.C.
  2. A.C. machines are simple , robust and do mot require much attention for their repairs and maintainance during their use.
  3. Wide range of voltages are obtained by the use of transformer.
  4. The magnitude of current can be reduced by using an inductance or a conductor without any appreciable loss of energy
  5. A.C. can easily be converted into D.C. with the help of rectifiers.
  6. When A.C. is supplied at higher voltages in long distance transmission , the line losses are small compared to a D.C. transmission


  1. Peak value of A.C. is high and it is dangerous to use so better insulation is required.
  2. It attracts person who touches it unlike D.C. which gives a repelling shock.
  3. An A.C. is transmitted from surface of the conductor and hence need several strands of thin wires insulated from each other.

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