Electrostatics Flashcards
(16 cards)
Difference between earthing negative charged sphere and positive charged sphere
Negative: Excess electrons flow from sphere to ground
Positive: Electrons from ground flow to sphere to neutralise excess positive charges
Electric force
the attractive or repulsive force that electric charges exert on one another
Electric field
A region in which an electric charge experiences an electric force
Direction of an electric field
the direction of the force that would act on a small positive charge
Electromotive force (emf)
work done by the source in driving a unit charge around a complete circuit
E=work done/amount of charge
Difference between series and parallel for EMF
Series: sum of sources
Parallel: constant
Potential difference
work done to drive a unit charge through the component
Resistance
Ratio of potential difference V across it to the current I flowing through it
Ohm’s Law
current passing through a metallic conductor is directly proportional to potential difference across it, provided that physical conditions (eg.temperature) remain constanto
Non-ohmic conductors
filament lamp and semiconductor diode
Difference between series and parallel for current
Series: same throughout
Parallel: sum of current in each individual branch=main current
Difference between series and parallel for resistance
Series: sum of all resistances
Parallel: 1/R1+ 1/R2=1/R
Input transducers
Electronic devices that convert non-electrical energy to electrical energy
why are filament lamps non-ohmic
Their resistance changes with temperature. In a filament lamp, the filament (usually made of tungsten) heats up as current flows through it. As the temperature of the filament increases, its resistance also increases, which means the relationship between the voltage and current is not linear.
induction
charging a conductor without contact
Potential Divider
A potential divider is a circuit that uses resistors in series to provide an output voltage that is a fraction of its input voltage.
