A-level Physics (Advancing Physics)/Charge

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Electrons, like many other particles, have a charge. While some particles have a positive charge, electrons have a negative charge. The charge on an electron is equal to approximately -1.6 x 10-19 coulombs. Coulombs (commonly abbreviated C) are the unit of charge. One coulomb is defined as the electric charge carried by 1 ampere (amp) of current in 1 second. It is normal to ignore the negative nature of this charge when considering electricity.

If we have n particles with the same charge Qparticle, then the total charge Qtotal is given by:

Qtotal = n Qparticle

By a simple rearrangement:

n = \frac{Q_{total}}{Q_{particle}}

Questions[edit]

1. How much charge do 1234 electrons carry?

2. How many electrons does it take to carry 5 C of charge?

3. The total charge on 1 mole of electrons (6 x 1023 particles) is equal to 1 faraday of charge. How many coulombs of charge are equal to 1 faraday?

4. The mass of a ball is 50mg. It is supplied 5C of charge. Will there be any change in the mass of the ball? If so, calculate the change of the mass.

Worked Solutions