A paisa coin is made up of Al-Mg alloy and weighs 0.75g. It has a square shape and its diagonal measures 17 mm. It is electrically neutral and contains equal amounts of positive and negative charges.

Treating the paisa coins made up of only Al, find the magnitude of equal number of positive and negative charges. What conclusion do you draw from this magnitude?

Given,

Mass of one paisa coin = 0.75 gm.

We know that,

Atomic mass of Aluminum = 27 gm.

And Avogadro’s number = 6.023 × 10²³

27 gm. of Aluminum contains 6.023 × 10²³ atoms of Aluminum

Number of atoms in (0.75 g of aluminum or) one paisa coin

No. Of protons in Aluminium=13

No. Of electros in Aluminium=13

Magnitude of charge of one atom=

Now,

Magnitude of charge one paisa coin= charge of one atom× number.

atoms in one paisa coin

We can be amazed by seeing that even a tiny amount of materials contain huge amount of charge.