AC vs DC currents / Changing Alternating Current to Direct Current
household electrical outlets deliver ?
Alternating current (AC)
Alternating current is better than direct current when ?
When it comes to transporting power over long distance
Direct current (DC) is also useful for?
many devices
60Hz
mean the generator makes 60 complete cycles in 1 second
Covalent
means that the atoms share electron orbits with adjacent atoms
P semiconductor
one section of a junction diode.
alternating currents can be stepped up or stepped down by using a ?
transformer
Frequency can also be expressed in ?
Megahertz or MHz and Kilohertz or kHz
One complete cycle of a generator is
1 Hertz
Kilohertz (kHz)
1000 hertz
Alternating current has a distinct advantage over direct current :
- it can be stepped up to obtain higher voltages and lower currents but still produce the same amount of power at the other end of the line - it can be transported over long distances through small wires because of the higher voltages and Lower currents
Alternating cycle
- one cycle would be voltage starting at zero -increasing to a maximum level in one direction -the decreasing to zero - increasing to a maximum level in the reverse direction - returning to zero again
Alternating current (AC) -
-Is when the current flowing in a conductor changes direction (moves back and forth) many times in a second -household electrical outlets deliver alternating current
Direct Current (DC) -
-Means that current only flows one way in a conductor. -This is the type of current that is delivered by a battery
Megahertz (MHz)
1 million hertz
Usually alternating current is generated at?
13,800 volts (V)
The development of the point contact transistor was announced in
1948
Other counties world use primarily (hertz/volts)
50 Hz electricity at 100-120 volts
in North America , alternating currents is always delivered at ?
60 cycles per second , this is also known as 60 hertz (Hz)
Japan uses both
60-Hz and 50Hz
Diode-
A device which allows current to flow in one direction but not the other
Semiconductor materials are used to make ?
A diode
End of the loops are connected to ?
A pair of slip rings
This dependence upon DC requires a source of ?
A source of inexpensive direct current for a variety of voltages and currents
Alternating currents is produced in an ?
AC generator , or alternator, through the interaction of magnetic fields and electric conductors.
The sine wave is the basic waveform of?
Alternating current or voltage
The radio frequencies that bring us radio and tv are also ?
Alternating currents (AC)
Metallic rectifiers may be used in ?
Battery chargers , instrument rectifiers , and many other applications including welding and electroplating.
Alternating current can be produce by simply ?
By simply rotating one or more turns of wire and a magnetic field.
The position of the conductor while rotating in a magnetic field determines?
Determines the magnitude and direction of the induced current.
What type of current is delivered by a battery ?
Direct current (DC)
As long as the loop is rotated in the magnetic field:
Electricity is produced
Electronics depend upon direct current (DC) for ?
For many of its circuit components
The turn of wire rotated in the magnetic field only will only generate?
Generate a small amount of electrical energy
What two chemical elements are used as the materials for semiconductor diodes ?
Germanium an silicon are used as materials for semiconductor diodes
The N material in a junction diode has?
Has an extra electron [ therefore the (-) or N designation] for every covalent bond of the material
Semiconductors can withstand
High voltages and carry large currents
Appliances may not function correctly or even safely if used?
If used on any thing other than the intended volt
The crystal structure of the resulting metallic chips or wafers permits current flow ?
In one direction only
The first use of the crystal semiconductor as a rectifier (detector) was ?
In the early days of the radio
Alternating Current (AC) is inexpensive which is why it's used
In thousands of devices
The loop is revolved (move around) at a constant speed by some external mechanical force , such as an?
Internal combustion engine, steam engine, water turbine, or electric motor
The length of the conductor in the magnetic field is ?
Is also constant (occurring continuously/ remaining the same)
Alternating current is a versatile type of power ?
It can be easily changed to the voltage or current needs of particular circuits
Sixty hertz (60Hz) means that?
Means that 60 complete voltage cycles like the one just describe take one place in one second.
What happens Once power reaches it's destination?
Once power reaches it's destination it is reduced to as low as 240 V for home use.
The P material in a junction diode has a deficiency of ?
One electron for every covalent bond of the material
In Large copper oxide rectifiers there are two sides
One side of the rectifier disk was copper and the other was copper oxide
Crystals of silicon or germanium are grown from a melt that includes small quantities of impure substances such as ?
Phosphorus , indium, boron , and other impurity or dopant atoms
North and Central American countries, along with a few North African countries and the northernmost South American countries use?
Primarily 60-Hz electricity at 100-120 volts.
The cooper oxide rectifier side allowing the current to flow in one direction produced?
Produced pulsating DC which was useful for a number of chemical processes and driving motors
Semiconductor varies in
Size from those that they are hard to see to those as large as two inches two inches diameter.
The junction diode handles larger power than
Than the point contact diode , but the junction diode has larger shunt ( push or pull) capacitance (C)
The connections to the junction diode consist of a lead to the P semiconductor material and a lead to ?
The N semi conductor
What factor is change as the coil is rotated ?
The angle , at which the conductor moves in relation to the magnetic lines of force
AC current Can be rectified (changed to DC/converted) in large cooper oxide rectifiers because
The cooper oxide rectifier side allow the current to flow in only one direction.
In Large copper oxide rectifiers, the copper allowed the current to flow easily , but the cooper oxide side:
The copper oxide side put up a great opposition to the flow of current in the other direction
The current in the load is the same as ?
The current induced in the rotating loop
Current determines ?
The size of the wire
Commercial radios , and television sets have been designed to utilized ?
Utilized the selenium type of metallic rectifier
A loop or a turn becomes apart of a complete electrical circuit whenever?
Whenever a Load is connected across the terminals of the loop
A 360 degree rotation of the loop will produce ?
Will produce a sine wave output
Power of the loop is conducted to the load through ?
a pair of brushes
the amplitude and direction of the current produces changes over time , forming a characteristic waveform or pattern know as ?
a sine wave
Large cooper oxide rectifiers were originally designed to ?
change the AC to DC
There are two types of electrical current:
direct current and alternating current
Alternating current is also important because ?
electronics devices rely so heavily on it
Junction diode -
first announced in 1949, consists of a junction between two dissimilar (not alike) sections of semiconductor material.
The word hertz means
frequency (cycles) per second so the words 1 second are not used with it
Point contact transistor
has a physical construction similar to the point contact diode but unlike the point contact diode it has a third lead with a metallic point contact which is placed near the other metallic point contact on the semiconductor
Flux density
is a constant that depends on the strength of the permanent magnet or electromagnet.
Hertz (Hz)
is a measurement of frequency , or the number of times the alternating current changes direction in one second.
AC electricity
the voltage and current that result from electromagnetic induction. ( when necessary it can be converted to DC)
sine wave-
waveform or pattern
