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### PWM full form

What is the full form of PWM?

• Pulse Width Modulation

What does PWM mean?

PWM is a form of signal processing, it is a technique for getting an analog result with digital means. Digital modulations are controlled is used to create a square wave, a signal switched between on and off.

### Difference between potential difference and EMF

We all know that the potential difference and electromotive force both in the form of energy. One of the major key difference between P.D and EMF is that the EMF is caused by converting the other form of the energy into electrical energy whereas in P.D is the difference the electrical energy is converted into other forms of energy some of the major difference is given below.

If you want to learn some different you are the right place for reading so keep reading for a few minutes for the right information regarding P.D and EMF.

## Definition of Potential Difference :

The potential difference is defined as the amount of energy can be used to moving from one point to another by one coulomb of charge. It is the measurement in volt and represented by the symbol of V.

## Definition of EMF :

Electromotive force: The EMF is the total voltage induced by the source. It is also the amount of energy supplied by the source to each coulomb of charge, It is measured in volts and represented by an E.

## Difference between P.D and EMF :

• EMF stands for electromotive force while P.D stands for potential difference.
• Potential difference is the difference of potentials between any two points in a closed circuit while EMF is the maximum potential difference between the two electrodes of the cell when no current drawn from the cell.i.e  when the circuit is open.
• P.D is the amount of energy used by the one coulomb of change while EMF force is the measure of the energy that it gives to each Colomb of change.
• P.D is the effect while EMF is the cause.
• P.D is a symbol of V, while EMF is the symbol of E.
• P.D does not remain constant, EMF remain constant.
• P.D is proportional to the resistance between the given point, EMF is independent of the resistance of the circuit.
• P.D is measured between any two points of the circuit while EMF is used only for the source of EMF.
• P.D is greater than EMF when the cell is being charged while EMF is greater than the potential difference between any two points in a circuit.
• P.D is less than the maximum voltage obtainable current from the cell, EMF is the maximum voltage that can be obtained from the cell.
• P.D is not responsible for the flow of steady current in the cell, EMF is responsible for the flow of steady current in the cell.
• P.D is represented by the voltmeter reading in a closed circuit(when the circuit is closed) while in EMF is represented by the voltmeter reading in an open circuit(when the switch is opened).
• A voltmeter is used for measuring the P.D while EMF meter is used for measuring the electromotive force.
• P.D  = E - IR, R= total external resistance while EMF (E) = I(R+r), R+r = Total external resistance and total internal resistance, I = total current
• Bothe P.D and EMF  are measured in volts(V).
• P.D loss the electrical energy in the circuit, EMF force gains the electrical energy in the circuit.
• P.D is directly depended on the resistance between two points of measurement while EMF does not depend on circuit resistance.
• P.D  is generated only in an electric field, EMF  is induced in the electric, magnetic and gravitational field.
• P.D is always less than the maximum possible value of EMF, EMF is the maximum voltage that battery can deliver whereas the magnitude of the P.D.
• P.D does not exist in the circuit when the magnitude of current remains zero while the EMF force exists in the circuit when the current does not flow in the circuit.
• The magnitude of the potential difference varies while the magnitude of EMF has always remained constant.
• The magnitude of electromotive force is always greater than potential difference when the circuit is unchanged but when the circuit is fully charged the magnitude of the potential difference is equal to the EMF of the circuit.

### Difference between decoder and demultiplexer

The key difference between a decoder and demultiplexer is that the former is a logic circuit that decrypted an encoded bitstream from one format into another, while the latter is a combination circuit that routes a single input line to multiple digital output line. Let us have a deep insight into the difference between decoder and demultiplexer.

Difference :
• The decoder is a logic circuit that decodes an encrypted input stream from one format to another while DEMUX is a combination circuit that used to implement general-purpose logic. It routes a single input signal to one of many output signals.
• The decoder is the inverse function of an encoder, which is translate coded digital input signals into equivalent coded output signals while DEMUX, on the other hand, does exactly the opposite of what a multiplexer does, which is to consolidate several data streams into a single stream of media or information.
• The decoder does not include select line while it is included in the demultiplexer.
• A decoder is used in the machine-specific language to change the instruction format while a routing device is used in the demultiplexer to route data from one signal to multiple signals.
• Decoding is employed data-intensive applications where data need to be changed into another form while demultiplexing is majorly implemented in the networking application.
• The decoder is generally categorized into 2 to 4 decoders, 3 to 8 decoders and 4 to 16 decoder while demultiplexer, on the other hand, is classified into 1-4 demultiplexers, 1-8 demultiplexer, and 1-16 demultiplexer.
• The decoder takes n input lines and produces 2^n out[ut lines, unlike an encoder which takes 2^n input lines and produces n output line whereas a demultiplexer transmits data from one line to 2^n  possible output lines, where the output line is determined by n select lines.
• Both multiplexer and demultiplexer are widely used in communication systems such as telecommunication and networking solutions. It receives the output signal from the multiplexer and converts it back into the original format. The decoder is used in a variety of applications such as wireless communication, data demultiplexing, memory address decoding and many more.

### Difference between active and passive sensors

What is an active sensor?

Active sensors create their own electromagnetic energy that is transmitted from the towards the terrain, interacts with the terrain producing a backscatter pf energy and is recorded the remote sensor's receiver.

What is a passive sensor?

The passive sensor detects the naturally emitted microwave energy within its field of view.

The main key difference between active and passive sensors are given below.

Active sensor :
• An active sensor is transducer generates electric current or voltage directly in response to environmental stimulation.
• Active sensor both transmit and measure electromagnetic energy.
• Active sensor self destructs during hijack attempts.
• Active sensor actively transmits measurement to ground stations whether the personnel on duty want the data or not.
• The active sensor emits their own EM energy which is transmitted towards the earth and receives energy reflected from the earth. The received EM(electromagnetic) energy is used for measurement purpose.
• It provides their own energy source for illumination.
• Active sensors are able to obtain measurement anytime.
• Example of active sensor like communication satellite, earth observation satellite, LISS -1, etc.
Passive sensor :
• The passive sensor is transducer produces a change in some passive electrical quantity such as capacitance, resistance or inductance as a result of the stimulation. These usually require additional electrical energy for excitation.
• The passive sensor only measures electromagnetic energy.
• The passive sensor has no defence against enemy attack.
• Passive sensors wait patiently until data are requested.
• The passive sensor receives naturally emitted EM energy within its field of view and performs measurement using it.
• Passive sensors can only be used to detect energy when naturally when the naturally occurring energy is available.
• Passive sensors can obtain measurement only in the day time.
• Example of passive sensor like remote sensing satellite, SPOT-1, LANDSAT-1, etc.

### Difference between multiplexer and demultiplexer

Multiplexer and demultiplexer are two common jargon in the network transmission field. This post will give you information about the difference between multiplexing and demultiplexing to better understand this topic. No matter whether you have any question about your network connection not, It is better to have a general understanding of them in case we need. Let us have a deep insight into the difference between multiplexer and demultiplexer.

What is multiplexer?

The multiplexer is a method in which more than one signal are combined into one signal that travels on a medium.
• It has so many inputs and one output.
• People call it MUX.
• It includes data selectors.
• In MUX the selection of particular input is controlled by a set of selection lines.
• Parallel to serial conversion.
• We don't need additional gates when designing multiplexers.
• Examples of multiplexer 8 input 1 output, 16 input 1 output, 32 input 1 output.

What is demultiplexer?

The demultiplexer is a reverse of multiplexing. In this method, a multiplexed signal is again decomposed in individual signals.
• It has one input and many outputs.
• People call it DEMUX.
• It includes data distributors.
• In DEMUX output line selection is controlled by bit values of n selection lines.
• Serial to parallel connection.
• Additional gates are included when designing de-multiplexer.
• Examples of demultiplexer 1 input 8 output, 1 input 16 output, 1 input 32 output.

Difference between MUX and DEMUX :

• MUX and DEMUX are that multiplexers are N to 1 device but demultiplexer is 1 to N device.
• Multiplexer with the help of control signals selects the particular input that has to be transmitted at the output. Demultiplexer utilized the control signal and allows us to have multiple outputs.
• Both MUX and DEMUX are combinational logic circuit used in the communication system but their operation is exactly reverse of each other as one operates on multiple inputs and other on a single input.
• In MUX system is an increasing the efficiency of the communication system by allowing the transmission data, such as audio and video data transmission while in DEMUX receive the output signals from the multiplexer and convert them back to the original form at the receiver end.

Conclusion :

From all, that above it is easier for you to tell the difference between multiplexing and demultiplexing. Both systems are bidirectional nature but the operation of the two are exactly opposite to each other. They are the reverse process of each and it can be applied to many occasions. So we conclude that both are two technologies widely used in CWDM and DWDM. The device used for multiplexing is a multiplexer and a device used for demultiplexing is a demultiplexer. Nowadays a typical device will have both MUX and DEMUX capabilities.

### Difference between volte and LTE

The terms LTE and VoLTE are often thrown around so much, especially when it comes to marketing, that their meaning is often confused and muddled so that they often don't understand what the terms mean or what they entail. Both are often used together for marketing but in reality, the two are completely different things though one is depended on the other.

VoLTE network supports both voice and data same time without hampering the other. Whereas the traditional LTE network may or may not support data and voice together or may affect the quality of the voice call.

The main key difference between VoLTE and LTE are given below.
• VoLTE stands for voice over LTE while LTE stands for long term evolution.
• VoLTE designed to carry both voice and data while LTE is primarily designed to be data-only technology.
• VoLTE support voice as well as data while LTE does not natively support voice transmission.
• In  VoLTE voice quality remains excellent when a data connection is on while the quality of voice reduce if the data connection is left on in LTE device.

Here this pose also give why VoLTE is better than LTE?
• Voice quality is better in VoLTE.
• VoLTE can connect calls faster.
• Use of VoLTE may save phone battery.
• VoLTE allows you video calls without using any third-party apps.
• You can keep the data connection on while making a voice call.

Summary:
• LTE is the next generation of mobile technology.
• LTE offers a high data transfer rate over a 4G network.
• VoLTE supports both voice and data simultaneously without affecting the quality of others.

### Difference between resistance and impedance

Definition of resistance and impedance:

Resistance is the opposition to the flow of electric current offered by a substance. It is represented by the R.

Impedance is total opposition to the flow of AC current because of any three components that are resistive, capacitive or inductive. It is represented by Z.

The basic difference between resistance and impedance is explained below keeping in mind the various factors like the basic definition of resistance and impedance, real and imaginary numbers, phase angle, power dissipation, and energy stored.

The main key difference between resistance and impedance are given below.
• Resistor occurs in both AC and DC circuit whereas impedance takes place the contribution of both resistance in an AC circuit.
• Resistance is the contribution of the resistive element in the circuit while the contribution of both resistance and reactance forms impedance.
• Resistance denoted by R while impedance denoted by Z.
• The opposition offered to the flow of current in an electric circuit whether AC or DC is known as the resistance, the opposition offered to the flow of current in an AC circuit because of resistance, capacitance and inductance are known as impedance.
• Impedance has both magnitude and phase angle whereas resistance does not have any phase angle.
• The resistance of the circuit does not vary according to the frequency of AC or DC whereas impedance varies with the change in frequency.
• Impedance is subjected to a magnetic field it represents both power dissipation and energy storage while resistance is an electromagnetic field represents power dissipation in any material.
• Resistance is a simple value consisting of only real number while the impedance of both real and imaginary numbers.
• Resistance is too much simple while in impedance will consider reactance in addition to resistance to determine it.
• Impedance may often take into consideration the overall circuit while resistance may or may not.
• Resistance is pure ohmic impedance.