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### Course: Physics library>Unit 11

Lesson 1: Charge and electric force (Coulomb's law)

# Triboelectric effect and charge

Explore the intriguing world of electrostatics with the triboelectric effect. Understand how rubbing a balloon on your hair leads to a transfer of electrons, creating positive and negative charges. Discover the concept of charge at an atomic level, and learn how protons, electrons, and neutrons play their part. You'll become familiar with the unit of charge, the coulomb, and its relationship to the elementary unit of charge.

## Want to join the conversation?

• Why was it decided that 1 C would equal 6.24 x 10^18 electrons? I realize that assigning the charge of 1 C to 1 electron would be impractical in daily life because we use such large currents, but who came up with that number and how?
• The Coulomb was initially defined based on the Ampere, which was then later determined to be approximately equal to that many electrons/protons. However, in the interest of making more accurate definitions, scientists are proposing to set the definition of the Coulomb, and thereby the Ampere, based on the fundamental charge.
• What "material(s)" are protons, or neutrons, or electrons made of?
• Protons and neutrons are composed of quarks. Quarks and electrons are fundamental particles and therefore not made of anything smaller as far as we currently know.
• I don't understand what charge is. An atom can have a charge because its electrons and protons have a charge. But what do we mean when we say that an electron has a charge? Why do they have a charge?
• Nithish,

A charge is a property of that particle, in the same way that the mass, and spin of a particle is also an inert property. As to why they have these properties, that's the real question.
• At 10.30. How is the reciprocal of the equation derived?
• You simply make a reverse of it. `1 / (6.24 * 10^18) = 1.6 * 10^-19`
• Why doesn't the hair tip attract with the bottom of the hair as both are oppositely charged?
• The hair is rooted to your skin, thus being grounded
• At when Sal said that 1C=6.24 * 10^18 why this value only? Any specific reason or formula?
• The formula is
Q= n.e or charge is equal to the number of electrons times the charge if 1 electron . To find the number of electrons in 1 C of charge we divide 1 from the charge of 1 electron , i.e, 1.6 *10^-19 . After solving it comes out to be 6.25*10^18 electrons
• At , in the atom model, wouldn't the electrons stick to the nuclei since Sal said different charges attract each other?
• That's because the electrons are orbiting. Means they're having enough speed to overcome electromagnetic forces but not enough speed to escape the atom.
• Have any idea of what force sticks together the protons inside a nuclear?