4.1 | charge and current

what is the SI base unit for electric current?

amperes

what is electric current?

the rate of flow of charge: I = Q/t.

what is the unit of charge and how is it defined?

charge is measured in coulombs, where 1 coulomb is the flow of charge in 1 second when the current is 1 ampere.

what happens to like and opposite charges?

like charges repel each other. opposite charges attract each other.

what is the elementary charge (e)?

1.6 x 10^-19 coulombs.

what is the charge of a proton and an electron?

a proton has a charge of +1, and an electron has a charge of -1, both representing multiples of the elementary charge.

how is the net charge of a particle determined?

the net charge Q is given by Q = ne, where n is the number of electrons added or removed.

what are charge carriers in metals?

electric current is carried by electrons, which move through a lattice of fixed positive ions.

what are electrolytes and how do they conduct electricity?

electrolytes are conducting liquids, that contain positive and negative ions, allowing current to flow when electrodes are placed in them.

what is conventional current and how does it differ from electron flow?

the flow of charge from positive to negative terminal, while in metals, electrons flow from negative to positive.

what does kirchhoff's first law state about currents in a circuit?

the sum of currents entering a point in a circuit equals the sum of currents leaving that point.

what is the mean drift velocity of electrons?

the average velocity of electrons as they move through a conductor, colliding with positive ions.

what does number density (n) represent in a material?

the number of free electrons per unit volume in a material.

how does the number density affect electron speed in conductors?

lower number density requires electrons to travel faster to carry the same current.

what is the formula for current in terms of number density, charge, and volume?

I = nAve

what is the relationship between the volume of a wire and its dimensions?

the volume of the wire is equal to its cross-sectional area multiplied by its length

how can the mean drift velocity be calculated?

mean drift velocity can be found using the rearranged formula I = nAve

what is the significance of charge conservation in electrical circuits?

charge cannot be created or destroyed, ensuring the total charge remains constant in a closed circuit.

what is the role of positive and negative electrodes in an electrolyte?

cations are attracted to the cathode (negative electrode) and anions are attracted to the anode (positive electrode), enabling current flow.

what is the effect of connecting a power supply to a metal conductor?

connecting a power supply attracts free electrons towards the positive terminal, creating an electric current.

what is the definition of charge in terms of protons and electrons in an atom?

in an atom, the number of protons equals the number of electrons, resulting in a neutral charge unless there is a gain or loss of electrons.

what happens when electrons are added or removed from an atom?

adding electrons produces a negative ion, while removing electrons produces a positive ion.

how does the direction of electron flow relate to conventional current?

electron flow is from negative to positive, which is opposite to the direction of conventional current.