T5 - electricity and Magnetism Flashcards
Coulomb’s law
the force between two point charges is proportional to the product go their charges and inversely proportional to the square of their separation
F=k (q1q2)/r2
current (I)
rate of flow of electric charges
drift velocity
the speed at which electrons move due to currents
electric field
a region of space what a charged object experiences a force due to its charge
electric field strength (E)
the force per unit charge experienced by a small positive test charge placed in the field
electron volt (eV)
the energy an electron would gain by being accelerated by a potential difference of 1 volt
emf
energy supplied per unit charge
internal resistance
the resistance of the components of the cell itself that leads to energy loss in the cell
Kirchhoff’s current law
at any junction in a circuit, the total current entering the junction equals the total current leaving
current:
enter = leaving
at junction
Kirchhoff’s voltage law
around any close path of a circuit, the total of all the potential differences (∆V) is zero
light dependent resisters (LDR)
a resistor whose resistance increases as light intensity decreases
Ohm’s Law
the current flowing through a piece of metal is proportional to the potential difference across it providing the temperature remains constant
potential difference (V)
the work done (or energy transferred) (W) when one unit of charge (q) moves between two points
primary cell
an electron cell that cannot be recharged
resistance (R)
the ratio of potential difference across the components to current flowing through the components
resistivity
a measure of hoe the substance opposes the flow of electric current
resistor
a component whose resistance is constant over a range of potential difference
secondary cell
an electric cell that can be recharged
strain gauge
a resistor whose resistance increases when stretched
terminal potential difference
potential inference measured across the terminals of a battery when it is part of a circuit and a current is flowing
thermistor
a resistor whose resistance increases as temperature decreases
cell
the longer line is the positive side
direction of conventional current
thumb - moving charge
direction of the velocity
fingers - moving charge
Magnetic field
palm surface
force
positive charge
use right hand
negative charge (electron)
use left hand
thumb - wires
direction of the current
finger - wire
magnetic field
