Current Electricity Flashcards
Voltage in power stations
5 × 10^5 volts
Voltage in homes
220 volts
voltage from eel
600 volts
Steady current
Continuous flow of electrons is called steady current
Electric Current
Directed flow of electrons
Current scalar or vector?
Scalar
Average speed of free electrons
10^5 m/s or several 100 km/s
Drift velocity?
The average velocity with which electrons get drifted in a metallic conductor under the influence of electric field.
10^-3 or 10^-5 m/s
Propagation of electric field speed?
At the speed of light.
Ohm’s law date?
by George Simone Ohm IN 1826
What should remain constant in ohms law?
Temperature, Physical state
Non ohmic
Filament of bulb,
semiconductor diode
Resistance depends upon?
Nature, dimensions, physical state of conductor
Slope of I-V graph gives?
1/R Conductance
Slope of non ohmic conductors
Decreases with increase of voltage
Graph bends upwards showing resistance decreases sharply as temperature increases
Thermistor
Resistance SI unit
Ohm
Conductance
SI: mho
Siemen (S)
Conductivity
per ohm per m
mho/m
Siemen/meter
S/m
Resistance increases with temperature:
Positive temperature coefficient
Pure metals
copper, aluminum etc.
Resistance decreases with temperature
Negative temperature coefficient
Insulators, electrolytes:
glass, mica, rubber etc.
semiconductors:
Carbon graphite, Silicon, Germanium
Potential at then ends of terminals a battery when circuit is open ?
(terminal potential difference)
emf
The influence that causes current to flow from lower to higher potential?
emf
Solar cell is also called
Radiant
emf of short circuit is?
zero
Maximum power output by?
Equal load resistance (R) and source resistance (r)
Max brightness depends upon?
series :
direct proportional to R
parallel :
inversely proportional to R
