Conceptual

Electricity and Magnetism Level 2

Two identical metallic spheres of exactly equal masses are taken. One is given a positive charge of $q$ coulombs and the other an equivalent negative charge. Which one will weigh more after charging?

Positively charged sphere Both will have exactly the same mass Negatively charged sphere

2 solutions

Akhil Bansal
Dec 9, 2015

Figure shows how postive charged is introduced in a sphere.

The positive charge of a body is due to deficient of electrons while the negative charge is due to surplus of electrons.
Hence,the mass of negatively charged sphere will be slighly more than that of the positively charged sphere.

Moderator note:

Great analysis. Just because it is negative, doesn't mean that it is less. We have to go back to first principles to understand what changed.

BUT it also can mean that protons are added to one and protons are removed from one so proton weighs more than electron thats why it can also be positive sphere

sid mehta - 5 years, 6 months ago

A proton is a subatomic particle present inside the nucleus.
You cannot add and remove proton.

Akhil Bansal - 5 years, 6 months ago

Isn't the mass of an electron negligible , in that case it should be the same weight. But if we consider the weight of the electron it's an other matter. You should put the remark of the weight of the electron in your problem ;)

Imad Fatimy - 5 years, 5 months ago

mass of electrons is negligible

Dev Sharma - 5 years, 6 months ago

But while comparing,we can consider mass of electron.

Akhil Bansal - 5 years, 6 months ago

hmm.. I see

Dev Sharma - 5 years, 6 months ago

Rushi Panmand
Dec 10, 2015

Positive charge is only introduced by removing electrons from the surface of any material. As electrons are removed from one sphere and are introduced on the other sphere, sphere which have negative charge will have more mass than the other who have positive charge.

Conceptual

2 solutions

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