4.1 charge and current Flashcards
what is electric current defined as?
the rate of flow of charge
what is the formula for electric current? and what is the unit?
I = ΔQ / Δt
amps/amperes, A
what is the unit of charge?
coulombs, C
what is one coulomb defined as?
one coulomb is defined as the amount of charge that passes in 1 second when the current is 1 ampere
what electrical component can you use in a circuit to measure the current?
e = 1.6 x 10^-19
what is the charge of an electron?
+e or 1.6 x 10^-19
what electrical component can you use in a circuit to measure the current?
an ammeter, measures in amps
what is the charge of a proton?
+e or 1.6 x 10^-19
what is the smallest unit of charge?
e - because the net charge of a particle or object is quantised (will always be a multiple of e)
in metals what are the charge carriers?
electrons, the movement of the electrons causing currents in the metal
what are solutions that can conduct electricity called?
electrolytes
what are the charge carries in electrolytes?
they are positive and negative ions
electrolytes are formed when ionic compounds, such as copper sulphate, are dissolved in water
what is conventional current and why is it different to actual current?
conventional current flows from the positive + terminal to the negative - terminal of the cell, which is in fact the opposite way to the actual flow of electrons
what is Kirchhoff’s first law?
the sum of the currents entering a junction must be equal to the sum of currents leaving a junction, because of conservation of charge
what is the rule behind Kirchhoff’s first law?
charge is always conserved
