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Electronics Engineering
Electronics Engineering is a branch of engineering that deals with practical applications of electronic components, devices, systems, or equipment. Electronics are devices that operate on low voltage sources, as in electron tubes, transistors, integrated circuits, and printed circuit boards and use electricity as part of its driving force.
24,372 Questions
What causes the current to decrease as an induction motor accelerates?
The current in an induction motor decreases as it accelerates due to reduced rotor impedance and increased back EMF. As the motor speeds up, the rotor reacts with the rotating magnetic field produced by the stator, causing a decrease in the current needed to maintain acceleration. This decrease in current helps to improve the motor's efficiency and reduce energy consumption.
Why are a range of voltages used?
Several reasons for different voltages. At the heart of it is that to deliver the same power, voltage and current are inversely related. The other aspect is safety.
So for the grid, high voltages are used to maximize power transmission within the current limits of the cables.
In industrial environments, equipment may require a lot of power - that requires high voltages as well
Domestic requirements are not so power-hungry so 120 or 240 volts are adequate, and are also safer (well... less dangerous) than higher voltages.
How do you make Light-dependent- resistance circuit?
A Light Dependent Resistor (aka LDR, photoconductor, or photocell) is a device which has a resistance which varies according to the amount of light falling on its surface.
A typical light dependent resistor is pictured above together with (on the right hand side) its circuit diagram symbol. Different LDR's have different specifications, however the LDR's we sell in the REUK Shop are fairly standard and have a resistance in total darkness of 1 MOhm, and a resistance of a couple of kOhm in bright light (10-20kOhm @ 10 lux, 2-4kOhm @ 100 lux).
Uses for Light Dependent ResistorsLight dependent resistors are a vital component in any electric circuit which is to be turned on and off automatically according to the level of ambient light - for example, solar powered garden lights, and night security lighting.An LDR can even be used in a simple remote control circuit using the backlight of a mobile phone to turn on a device - call the mobile from anywhere in the world, it lights up the LDR, and lighting (or a garden sprinkler) can be turned on remotely!
Light Dependent Resistor CircuitsThere are two basic circuits using light dependent resistors- the first is activated by darkness, the second is activated by light. The two circuits are very similar and just require an LDR, some standard resistors, a variable resistor (aka potentiometer), and any small signal transistorIn the circuit diagram above, the LED lights up whenever the LDR is in darkness. The 10K variable resistor is used to fine-tune the level of darkness required before the LED lights up. The 10K standard resistor can be changed as required to achieve the desired effect, although any replacement must be at least 1Kto protect the transistor from being damaged by excessive current.
By swapping the LDR over with the 10K and 10K variable resistors (as shown above), the circuit will be activated instead by light. Whenever sufficient light falls on the LDR (manually fine-tuned using the 10K variable resistor), the LED will light up.
Using an LDR in the Real WorldThe circuits shown above are not practically useful. In a real world circuit, the LED (and resistor) between the positive voltage input (Vin) and the collector (C) of the transistor would be replaced with the device to be powered.Typically a relay is used - particularly when the low voltage light detecting circuit is used to switch on (or off) a 240V mains powered device. A diagram of that part of the circuit is shown above. When darkness falls (if the LDR circuit is configured that way around), the relay is triggered and the 240V device - for example a security light - switches on.
NEW For details of a more advanced light/dark sensor circuit click here to read our new article LM741 Light/Dark Sensor Circuit. We have these circuits available for sale.
How do you convert 24 vac to 5 vac?
You can use a transformer with a turns ratio of 24:5 to convert 24 VAC to 5 VAC. This means the primary winding has 24 turns for every 5 turns on the secondary winding, which will step down the voltage proportionally. Make sure the transformer is rated for the appropriate power and frequency.
What is a transformer called that increases voltage?
A transformer that increases voltage is a step-up transformer.
Device that can both transmit and receive a radio signal?
A transceiver is a device that can both transmit and receive a radio signal. It combines both functions in a single unit, allowing for two-way communication over radio frequencies. Transceivers are commonly used in applications such as two-way radios, walkie-talkies, and wireless communication systems.
The constant flow of electrons through a complete circuit?
The constant flow of electrons through a complete circuit is known as electric current. It is measured in amperes (A) and is driven by a voltage difference between two points in the circuit. The flow of current allows electrical energy to be transferred and used to power devices.
Conductivity in a metal results from the metal atoms having?
Conductivity in a metal results from the metal atoms having loosely held electrons that are free to move and carry electric charge. These free electrons can easily flow through the metal lattice, allowing for the efficient transfer of electrical energy.
The settings on your battery charger may vary the charge voltage (e.g. 6V and 12V) or the charge rate (e.g. 2A and 6A). Because you say that your charger has three settings, I would guess that either the charge voltage is fixed at 12V (and you have 3 choices for charge rate) or you have one setting for 6V and two choices for charge rate at 12V.
Make sure the voltage is set to the markings on your battery. This is most likely 12V, but it's best to make sure. If you can't match the setting (you have a 12V only charger and your battery is 6V), you must use another charger or you are likely to damage the battery and to risk explosion.
The charge rate setting is meant to allow you to charge batteries of different sizes. A lawn tractor battery probably should be set at the lowest charge rate, say 2A. Larger batteries, like the one in your car, can be charged at higher rates. Charging at a low rate prevents the build-up of heat in the battery and reduces the risk of damage.
Should the capacitors used in electronic circuits have a minimum voltage rating of 25 volts?
Capacitors used in electronic circuits need not have a minimum voltage rating of 25 volts. Electronic circuits powered by batteries at 12 volts and below should work fine with capacitors rated at 15 volts.
A common cathode is a shared terminal in a multiple LED or display device where all the cathodes of the individual LEDs are electrically connected. This configuration allows for the LEDs to be controlled independently through their anodes.
Which values of resistance is correct ac or dc?
AC current tends to flow towards the surface of a conductor due to what is known as the skin effect. This phenomenon acts to reduce the effective cross-sectional area of a conductor and, therefore, elevate its resistance. This elevated value of resistance is known as AC resistance.
The skin effect increases with frequency. At 50/60 Hz, the skin effect is quite moderate and, so, the AC resistance is not significantly higher than the true (or DC) resistance of the conductor.
As to 'which value of resistance is correct?' Well, the natural resistance of a conductor is directly-proportional to its cross-sectional area and resistivity, and inversely-proportional to its length and the type of current plays no part in this. This is the value that a DC current would 'see', so you could say that this would be the 'correct' value of resistance.
Why electrons flow in negative to positive direction?
Electrons are negatively charged particles. The reason the negative side of your D battery is negative is because that's where the free electrons are. The positive terminal is starved or has a deficit of electrons. The negatively charged electrons naturally want to fill the 'holes', in atoms lacking an electron on the positive side. Thus electron flow is from negative to positive. Conventional current flow assumes that current flows out of the positive terminal, through the circuit and into the negative terminal of the source. This was the convention chosen during the discovery of electricity. They were wrong!
Which of all the metals are not conductive?
all metals in pure form are conductive, that's because they will always have free electrons circling around them ready to be used as electricity.
An ammeter is used to measure the intensity of current flow in a circuit or branch in a circuit. It is wired in series with the circuit being evaluated to accurately measure the current passing through that specific part of the circuit.
104VAC is the highest voltage less than 115VAC minus 10%, which is 104.5VAC. 127VAC is the lowest voltage greater than 115VAC plus 10%, which is 126.5VAC. Plus or minus 10% is considered to be the design basis range of standard 115VAC equipment, in order to maintain correct operation.
What is a circuit called if its operating and the current is flowing?
A closed circuit is one where the current is flowing continuously from the source to the load and back to the source, completing a loop. An open circuit, on the other hand, is one where the current cannot flow because the circuit is broken at some point.
Total internal reflection occurs when the incident angle is greater than the critical angle, causing light to be reflected back inside the medium rather than refracting out of it. This phenomenon is commonly seen in prisms and optical fibers.
Does snow or leaves obstruct a RFID reader?
Yes, but the impact depends on the frequency and type of antenna. It's mainly the effect of free water absorbing the RF energy.
Low frequency near field systems have very little problem with water, while higher frequency far field systems can be completely stopped by wet leaves or free water.
copper oxide is a semiconductor. it used to be used for power rectifiers.
What is the flow of electrons is called?
The flow of electrons is called electric current. It is the movement of electric charge through a conductor, such as a wire, in response to an electric field.
1. Voltmeter has high impedance and hence will restrict the current severely.
a) Electric Bulb will not glow
b) The Ammeter will just measure the current that Voltmeter allows and since this current is much smaller than actual current nothing will happen to ammeter.
c) The Voltmeter will measure the Voltage that is being applied.
d) This will allow you to measure the resistance of the Voltmeter.
VR=V/I
What conditions are needed for a current to flow?
For a current to flow there must be a voltage, and a conductor through which the current can pass.
