coulombs

(noun)

In the International System of Units, the derived unit of electric charge; the amount of electric charge carried by a current of 1 ampere flowing for 1 second. Symbol: C.

Related Terms

Examples of coulombs in the following topics:

  • Electrolysis Stoichiometry

    • From the perspective of the voltage source and circuit outside the electrodes, the flow of electrons is generally described in terms of electrical current using the SI units of coulombs and amperes.
    • It takes 96,485 coulombs to constitute a mole of electrons, a unit known as the faraday (F).
    • current (in amperes) is the rate of charge transport: 1 amp = 1 $\frac {Coulombs}{second}$.
    • $1.5\ hours \times \frac {3600\ seconds}{1\ hour} \times \frac {.22\ Coulombs}{second} \times \frac {1\ mole\ e^-}{96485\ Coulombs} \times \frac {1\ mole\ Cu^{2+}}{2\ mole\ e^-} \times \frac {63.54\ grams\ Cu}{1\ mole\ Cu} =$
    • $0.39\ g\ Cu \times \frac {1\ mole\ Cu}{63.54\ g\ Cu} \times \frac{2\ moles\ e^-}{1\ mole\ Cu^{2+}} \times \frac {96485\ Coulombs}{1\ mole\ e^-} = 1184\ Coulombs$

  • Solving Problems with Vectors and Coulomb's Law

    • Coulomb's Law, which calculates the electric force between charged particles, can be written in vector notation as $F(E) = \frac{kq_1q_2}{r^2}$ r+.
    • Coulomb's Law using vectors can be written as:
    • Applying Coulomb's Law three times and summing the results gives us:
    • Coulomb's Law applied to more than one point source charges providing forces on a field charge.
    • Explain when the vector notation of Coulomb's Law can be used

  • Gauss's Law

    • Gauss's law can be used to derive Coulomb's law, and vice versa.
    • Note that since Coulomb's law only applies to stationary charges, there is no reason to expect Gauss's law to hold for moving charges based on this derivation alone.
    • In fact, Gauss's law does hold for moving charges, and in this respect Gauss's law is more general than Coulomb's law.
    • In fact, any "inverse-square law" can be formulated in a way similar to Gauss's law: For example, Gauss's law itself is essentially equivalent to the inverse-square Coulomb's law, and Gauss's law for gravity is essentially equivalent to the inverse-square Newton's law of gravity.

  • Spherical Distribution of Charge

    • The mathematical formula for the electrostatic force is called Coulomb's law after the French physicist Charles Coulomb (1736–1806), who performed experiments and first proposed a formula to calculate it.
    • Modern experiments have verified Coulomb's law to great precision.
    • Coulomb's law holds even within the atoms, correctly describing the force between the positively charged nucleus and each of the negatively charged electrons.
    • An electric field is a vector field which associates to each point of the space the Coulomb force that will experience a test unity charge.
    • Describe shape of a Coulomb force from a spherical distribution of charge

  • Properties of Electric Charges

    • Its SI unit is known as the Coulomb (C), which represents 6.242×1018e, where e is the charge of a proton.
    • This is known as Coulomb's Law.
    • The formula for gravitational force has exactly the same form as Coulomb's Law, but relates the product of two masses (rather than the charges) and uses a different constant.
    • The forces (F1 and F2) sum to produce the total force, which is calculated by Coulomb's Law and is proportional to the product of the charges q1 and q2, and inversely proportional to the square of the distance (r21) between them.

  • Superposition of Forces

    • For Coulomb's law, the stimuli are forces.
    • The scalar form of Coulomb's Law relates the magnitude and sign of the electrostatic force F, acting simultaneously on two point charges q1 and q2:
    • The principle of linear superposition allows the extension of Coulomb's law to include any number of point charges—in order to derive the force on any one point charge by a vector addition of these individual forces acting alone on that point charge.

  • Free Energy and Cell Potential

    • Here, n is the number of moles of electrons and F is the Faraday constant (96,485$\frac {Coulombs}{mole}$).
    • One volt is $1\frac {Joule}{Coulomb}$.
    • $\Delta G^o = -2 \ moles\ e^- \times 96485\frac {Coulombs}{mole} \times 0.12 \frac {Joules}{Coulomb}$

  • Nerve Conduction and Electrocardiograms

    • Diffusion of K+ and Cl− thus creates the layers of positive and negative charge on the outside and inside of the membrane, and the Coulomb force prevents the ions from diffusing across in their entirety .
    • The result is two layers of charge right on the membrane, with diffusion being balanced by the Coulomb force.
    • The membrane thus temporarily becomes permeable to Na+, which then rushes in, driven both by diffusion and the Coulomb force.
    • This is an example of active transport, wherein cell energy is used to move ions across membranes against diffusion gradients and the Coulomb force.
    • Diffusion moves the K+ and Cl− ions in the direction shown, until the Coulomb force halts further transfer.

  • Stress and Strain

    • A point charge creates an electric field that can be calculated using Coulomb's Law.
    • The above mathematical description of the electric field of a point charge is known as Coulomb's Law.

  • Electric Field from a Point Charge

    • A point charge creates an electric field that can be calculated using Coulomb's law.
    • The above mathematical description of the electric field of a point charge is known as Coulomb's law.