rheostat- variable resistor, made from coils of wire, you can change resistance
a thiliment bulb does not obey Ohm's law
1 of 8
Potential Dividers
potential dividers - used to produce a required voltage in a circuit
2 fixed resistors can be used as a potential divider
2 of 8
Thermistors & LDRs
thermistor - resistor dependent on temperature , if temperature if high, resistance if low, a negative temperature is efficent
LDR- resistor dependent on light intensity
3 of 8
Transistors
transistors - an electrical switch, it can be turned on or off. An average computer has millions of transistors
When the base & emitter voltage = 0 or low, no current flows in base-emitter
This means no current can flow between collector & emitter
When voltage of base & emitter = high a small current flows through base-emitter
this allows large current in collector & emitter
a small current in base emitter acts like a switch that 'turns on' the large current in collector
emitter current = base collector + collector current
4 of 8
LED (Light Emitting Diode)
use semi-conductors that are particularly arranged to allow current to pass one way
light is emitted when a current flows through the semi conductors
an NPN transistor can be used as a switch for LEDs when connected with 3 reistors
a resistor is connected in parllel to limit current, preventing damage
no current in base cuaes transistor to switch off so the LED switchs off
when small current is in base it causes transmitter to turn on, so large current can flow into collector emitter, so LED lights up
5 of 8
Logic Gates
AND gate OR gate NOT gate
Nand gate Nor gate
a relay switchs mains current, so the low power logic gate would not be directly exposed to mains power preventing damage. The relay isolates the low voltage in the sensing circuit from the high voltage.
6 of 8
Generators
all generators generate AC current
factor effecting:
if you double the turns, you double the voltage
double speed and the voltage doubles, if you increase the speed, you increase the number of rotations per second therefore increasing the frequency
mains frequency = 50Hz
7 of 8
Transforming and Charging
electrons move into the positive space & flow making a current
this doesn't happen if current is in a negative direction or if current is positive it causes the electrons in layer N to move to layer P
diode capacitor diode resistance graph
negative current is blocked by high resistance diode
Electricity is one of the most important elements in the life of humans. It can be used for different purposes, depending on what you want to do with it. In this article, you can check https://www.easygates.co.uk/product-category/electric-gates/ and take a look at how electricity can be used in gadgets and what types of gadgets use electricity. The electricity that is used in gadgets today has been developed to a large extent.
Comments
Report