Electric Charge
What is electric charge?
Electric charge generates
electric field. The electric charge influence other
electric charges with electric force and influenced by the other
charges with the same force in the opposite direction.
There are 2 types of electric charge:
Positive charge (+)
Positive charge has more protons than electrons (Np>Ne).
Positive charge is denoted with plus (+) sign.
The positive charge attracts other negative charges and
repels other positive charges.
The positive charge is attracted by other negative
charges and repelled by other positive charges.
Negative charge (-)
Negative charge has more electrons than protons (Ne>Np).
Negative charge is denoted with minus (-) sign.
Negative charge attracts other positive charges and repels
other negative charges.
The negative charge is attracted by other positive
charges and repelled by other negative charges.
Electric force (F) direction according to charge type
| q1/q2 charges |
Force on q1 charge |
Force on q2 charge |
|
| - / - |
←⊝ |
⊝→ |
repletion |
| + / + |
←⊕ |
⊕→ |
repletion |
| - / + |
⊝→ |
←⊕ |
attraction |
| + / - |
⊕→ |
←⊝ |
attraction |
Charge of elementary particles
| Particle |
Charge (C) |
Charge (e) |
| Electron |
1.602×10-19 C |
-e |
| Proton |
1.602×10-19 C |
+e |
| Neutron |
0 C |
0 |
Coulomb unit
The electric charge is measured with the unit of Coulomb [C].
One coulomb has the charge of 6.242×1018
electrons:
1C = 6.242×1018 e
Electric charge
calculation
When electric current flows for a specified time, we can
calculate the charge:
Constant current
Q = I · t
Q is the electric charge, measured in
coulombs [C].
I is the current, measured in amperes
[A].
t is the time period, measured in
seconds [s].
Momentary current

Q is the electric charge, measured in
coulombs [C].
i(t) is the momentary current,
measured in amperes [A].
t is the time period, measured in
seconds [s].
See also