Define EMF and state its unit.

Define EMF and state its unit.
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1 Answer

Answer :

Electromotive force(EMF): A potential difference generated by a source of electrical energy across its terminals which tends to produce an electric current in a circuit is called electromotive force.

Unit of EMF is Volt
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Related questions

Explain statically induced EMF and Dynamically induced EMF with neat diagrams.

Description : Explain statically induced EMF and Dynamically induced EMF with neat diagrams.

Last Answer : Statically Induced EMF:- When changing magnetic field links with a stationary coil an emf is induced. This emf is called statically induced emf. Statically induced EMF is of two types: Self-induced ... cuts the field and an emf is induced. This emf is called dynamically induced emf.    

Write emf equation of a transformer.

Description : Write emf equation of a transformer.

Last Answer : E.M.F equation of transformer is given by where Фm= Maximum value of ac flux linking with primary and secondary winding. f = frequency of applied ac signal N= number of turns on primary or ... in primary = E1=4.44 Фm f N1volts  Voltage induced in primary = E2=4.44 Фm f N2volts

List the types of induced emf.

Description : List the types of induced emf.

Last Answer : The types of induced emf are : i) Statically induced emf , ii) Dynamically induced emf

Define filter and state it’s types.

Description : Define filter and state it’s types.

Last Answer : A filter circuit may be defined as a circuit, which removes (or minimizes)the unwanted a.c. component of the rectifier output and allows only the d.c. component to reach the load. Types of filters 1) ... 2) Choke input filter(series inductor filter) 3) LC filter 4) π Filter 5) RC filter

Define transformation ratio of a transformer.

Description : Define transformation ratio of a transformer.

Last Answer : Transformation Ratio (K) of a transformer: It is the ratio of secondary number of turns to primary number of turns. (OR) It is the ratio of secondary voltage to primary voltage. (OR ) It is the ratio of primary current to secondary current. OR

Define FHP motor and list various types.

Description : Define FHP motor and list various types.

Last Answer : Any motor rated less than one horse power may be called as fractional horse power motors(FHP) various types of FHP motors are: 1.Split phase induction motor 2. Capacitor start induction motor 3. Capacitor start capacitor run induction motor 4. Shaded pole induction motor. 

Define (i) Permeability (ii) Reluctance.

Description : Define (i) Permeability (ii) Reluctance.

Last Answer : Permeability: The capability of the magnetic material to conduct the magnetic flux is known as permeability (OR) It is defined as ratio of magnetic flux density B in a medium to the magnetic flux intensity ... as the property of a material due to which it opposes the creation of magnetic flux in it.

Define passive components and classify them.

Description : Define passive components and classify them.

Last Answer : Passive components: The components which by themselves are not capable of amplifying (or processing) electrical signals are known as passive components. They require external energy source for their functioning. These are bidirectional devices.  Classification: Resistors, Capacitors, Inductors etc.

Define: (i) Efficiency (ii) Voltage regulation of transformer.

Description : Define: (i) Efficiency (ii) Voltage regulation of transformer.

Last Answer : i) Efficiency : It is the ratio of output power to the input power of the transformer.It is denoted by η. ii) Voltage Regulation of transformer: The ratio of the change in Secondary Terminal ... So where, VNL = No Load Secondary voltage VFL = Full load secondary voltage

Define: (i) Inductive reactance (ii) Impedance.

Description : Define: (i) Inductive reactance (ii) Impedance.

Last Answer : i) Inductive reactance: Inductive reactance is the opposition offered by an inductor to alternating current . It is denoted by XL and given by XL = 2πf LΩ = ωL Ω ii)Impedance: It is the total opposition offered to flow of AC current in an AC circuit. It is denoted by Z and the unit is ohm. 

Define: (i) Electromagnetism (ii) Magnetic flux.

Description : Define: (i) Electromagnetism (ii) Magnetic flux.

Last Answer : i)Electromagnetism : It is the magnetism generated by electricity. OR  It is defined as the phenomenon associated with electric and magnetic fields and their interactions with each other. ii) Magnetic flux : The total number of magnetic lines of force in a magnetic field is called magnetic flux.

State the applications of BJT.

Description : State the applications of BJT.

Last Answer : Applications of BJT: 1. As a switch 2. As an amplifier 3. As a multivibrator 4. As a oscillator 5. As a timer circuit 6. As a Logic circuits 7. Delay circuits

Explain the working of auto-transformer and state any two advantages of it.

Description : Explain the working of auto-transformer and state any two advantages of it. 

Last Answer : Working of auto transformer :-It is a transformer with one winding only, part of this being common to both primary and secondary. In this transformer the primary and secondary are not electrically ... are less, so the efficiency of auto transformer is higher than that of two winding transformer.

State the need for filters and list the different types of filters.

Description : State the need for filters and list the different types of filters.

Last Answer : Need for filters 1) Output of all rectifiers is pulsating dc voltage and most of citcuits which work on dc requires pure dc voltage. 2) So in order to get pure dc waveform, filters are connected at the ... 2) Choke input filter(series inductor filter) 3) LC filter 4) π Filter 5) RC filter

State why transistor is called as a bipolar device.

Description : State why transistor is called as a bipolar device.

Last Answer : In case of transistor (BJT), the current conduction takes place due to both electrons and holes, ie, due to both positive as well as negative polarity charge carriers. Therefore transistor is called a bipolar device. 

State Faraday's first and second law of electromagnetic induction.

Description : State Faraday's first and second law of electromagnetic induction.

Last Answer : i)Faraday's First Law: Whenever a conductor cuts the magnetic lines of force or is cut by the magnetic lines of force or flux linking with conductor changes, an emf is induced in the conductor.  ... Law: The magnitude of induced emf is directly proportional to the rate of change of flux.

State the types of single phase induction motors.

Description : State the types of single phase induction motors.

Last Answer : The types of single phase induction motors are: i) Resistance split phase induction motor. ii) Capacitor split phase inductor motor. a. Capacitor start induction run motor b. permanent capacitor motor c. capacitor start capacitor run induction motor iii) Shaded pole induction motor.

State the working principle of I ø transformer.

Description : State the working principle of I ø transformer.

Last Answer : Working principle of transformer : Transformer works on the principle of mutual electromagnetic induction. When AC voltage is applied to the primary winding of a transformer it causes ac current to flow ... in the secondary winding. The current flows in the secondary circuit if load is connected.

Explain the operation of transistor as a switch and as an amplifier, with neat circuit diagrams.

Description : Explain the operation of transistor as a switch and as an amplifier, with neat circuit diagrams. 

Last Answer : Explanation of transistor as a switch: The transistor can be used for two types of application viz. amplification and switching. For the amplification, transistor is biased in its active region. ... results in a large output voltage, which shows that the transistor works as an amplifier.

Explain the operation of a full wave bridge rectifier with π filter using a neat diagram. Draw input and output waveforms.

Description : Explain the operation of a full wave bridge rectifier with π filter using a neat diagram. Draw input and output waveforms.

Last Answer : During positive half-cycle of input, the secondary voltage VAB is positive, so diodes D1 and D2 forward biased and D3 and D4 reverse biased. The load current flows from terminal A ... smooth DC voltage appears across the load. The input and output waveforms are shown in the figure.

List any 4 advantages and any 4 disadvantages of Integrated circuits.

Description : List any 4 advantages and any 4 disadvantages of Integrated circuits.

Last Answer : Advantages of Integrated circuits:- 1. Extremely small size. 2. Very small weight . 3. Very low cost . 4. More reliable . 5. Lower power consumption . 6. Easy replacement ... achieved.  9.Large value of saturation resistance of transistors. 10.Voltage dependence of resistor and capacitors.

Draw the output characteristics of BJT in CE configuration and label various regions on it.

Description : Draw the output characteristics of BJT in CE configuration and label various regions on it.

Last Answer :  output characteristics of BJT in CE configuration 

Draw the block diagram of regulated power supply.

Description : Draw the block diagram of regulated power supply.

Last Answer : Block diagram of regulated power supply:

List different types of resistors and capacitors.

Description : List different types of resistors and capacitors.

Last Answer : Types of Resistors: 1. Carbon Composition resistor 2. Thin film resistor 3. Thick film resistor 4. Wire wound resistor 5. Thermistor 6. LDR 7. Photo resistor Types of capacitors: 1 ... capacitor 2. Variable capacitor 3. Air ganged capacitor 4. PVC ganged capacitor 5. Trimmer capacitor

Write the relation between RMS value and Average value.

Description : Write the relation between RMS value and Average value.

Last Answer : The ratio of RMS value to average value is called the form factor of an alternating quantity.

Draw: (i) Input characteristics of transistor in CE mode. (ii) Output characteristics of transistor in CE mode and show different regions on it.

Description : Draw: (i) Input characteristics of transistor in CE mode. (ii) Output characteristics of transistor in CE mode and show different regions on it.

Last Answer : (i) Input characteristics of transistor in CE mode.   (ii) Output characteristics of transistor in CE mode and show different regions on it.  

Draw and explain: bridge rectifier with shunt capacitor filter.

Description : Draw and explain: bridge rectifier with shunt capacitor filter.

Last Answer : Operation of bridge rectifier with capacitor filter is explained in different intervals with the help of the following wave form. Operation in interval at 0 to A: ... filter is very close to theideal dc voltage waveform as most of the ripple is removed from rectified output.

Explain ideal voltage source with suitable diagram.

Description : Explain ideal voltage source with suitable diagram.

Last Answer : A voltage source is a two terminal device which can maintain a fixed voltage. An ideal voltage source can maintain the fixed voltage independent of the load resistance or the output current. ... the terminal voltage remains constant equal to V volts without load (RL = ∞) or with load

List the different transistor configurations.

Description : List the different transistor configurations.

Last Answer : The three different transistor configurations are, 1. Common emitter configuration(CE) 2. Common base configuration(CB) 3. Common collector configuration(CC)

List any two applications of LED.

Description : List any two applications of LED.

Last Answer : 1) LEDs are used in 7 segment display and dot matrix display. 2) They are used in opto couplers. 3) They are used for indicating power ON/OFF conditions. 4) They are used in infrared remote controls. 5) They are used as indicators in various electronic circuits.

Compare analog and digital ICs.

Description : Compare analog and digital ICs.

Last Answer : Sr. No. Analog ICs Digital ICs  1 Analog ICs accept and output analog data through its pins. Digital ICs deal with only logic data inputs and outputs.  2 Almost every ... IC for dedicated application. Works with TTL logic level and works in voltage range of 0-5V only.

Compare autotransformer with two winding transformer.

Description : Compare autotransformer with two winding transformer.

Last Answer : Two winding transformer Auto transformer 1.It has two separate windings : a) primary, b)secondary.  1. An auto transformer has single winding which acts both as primary and secondary ... varied. 3. They find application as boosters in AC feeders to increase the voltage levels.

With the help of waveforms and phasor diagrams, show the phase relationship between voltage and current in pure inductive circuit.

Description : With the help of waveforms and phasor diagrams, show the phase relationship between voltage and current in pure inductive circuit.

Last Answer : Phasor Diagram:  

State the SI unit of potential difference and emf.

Description : State the SI unit of potential difference and emf.

Last Answer : The SI unit of potential difference and emf is volt.

(a) Define permeability. (b) Define MMF. (c) Define form factor of an alternating quantity. (d) Define frequency and time period of an alternating quality. (e) Define transformation ratio of transformer. (f) State the EMF equation of a 1 transformer and state the meaning of each term used. (g) Give two applications of single phase motors.

Description : (a) Define permeability. (b) Define MMF. (c) Define form factor of an alternating quantity. (d) Define frequency and time period of an alternating quality. (e) Define transformation ratio of transformer. ... and state the meaning of each term used. (g) Give two applications of single phase motors. 

Last Answer : Permeability : It is the ability of a magnetic/Non magnetic material to allow setting up of flux in it.  MMF : The magneto motive force (MMF) is the force required to setup flux in a magnetic / ... applications of single phase motors : Water pumps, ceiling fan, lathe machine

The unit of apparent power in a purely inductive circuit is called the _____________. A. kva B. var C. emf D. watt

Description : The unit of apparent power in a purely inductive circuit is called the _____________. A. kva B. var C. emf D. watt

Last Answer : Answer: B

Define self induced Emf. Write equation of self induced Emf.

Description : Define self induced Emf. Write equation of self induced Emf. 

Last Answer : Definition: Self-induced emf is the e.m.f induced in the coil due to the change of flux produced by linking it with its own turns. Or Self induced emf is that which is induced in a coil, due to the change in its own current or flux. Self induced emf equation. E = - N (dΦ/dt) volts

Define self and mutual induced emf.

Description : Define self and mutual induced emf.

Last Answer : Self-induced emf: Self-induced emf is the e.m.f induced in the coil due to the change of flux produced by linking it with its own turns. Mutual induced emf: The emf induced in a coil due to the change of flux produced by another neighbouring coil linking to it, is called Mutually Induced emf.   

Define: 1) statically induced EMF 2) dynamically induced EMF

Description : Define: 1) statically induced EMF 2) dynamically induced EMF Write the names of equipments in which these two types of EMF get induced

Last Answer : Concept of statically induced emf: The emf induced in coil or conductors without any relative motion between it and magnetic field is called statically induced emf. When conductor is stationary and flux ... it. This emf is dynamically induced emf. e.g. Emf induced in generators, alternator.

Write the Emf equation of transformer. State the meaning of each term in it.

Description : Write the Emf equation of transformer. State the meaning of each term in it. 

Last Answer : EMF equation of Transformer:- E1 = 4.44 f ØmN1 OR E1 = 4.44 f BmAN1 E2 = 4.44 f ØmN2 OR E2 = 4.44 f Bm AN2 Let, E1 = Primary emf E2 = Secondary emf N1= Number of turns in the primary N2 ... flux in core (wb) Bm= Flux density (wb/m2 /Tesla) A= Area of cross section of core m2 F = Frequency 

Explain concept of back emf in DC machine. State how it governs armature current.

Description : Explain concept of back emf in DC machine. State how it governs armature current. 

Last Answer : Back emf: When the armature of DC machine rotates under the influence of driving torque, the armature conductors move in the magnetic field and cut it and hence emf is induced in them. The ... flow of armature current i.e. it automatically changes the armature current to meet load requirements.

The emf of a battery is 4.0 V and its internal resistance is `1.5 Omega`. Its potential difference is measured by a voltmeter of resistance `1000 Omeg

Description : The emf of a battery is 4.0 V and its internal resistance is `1.5 Omega`. Its potential difference is measured by a voltmeter of resistance `1000 Omeg

Last Answer : The emf of a battery is 4.0 V and its internal resistance is `1.5 Omega`. Its potential ... percentage error in the reading of emf shown by voltmeter.

A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field with its plane perpendicular to the field. An emf is

Description : A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field with its plane perpendicular to the field. An emf is

Last Answer : A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field ... . the loop is deformed from the original shape

What is terminal potential differnce of a cell? Can its value be greater than the emf of a cell? Explian.

Description : What is terminal potential differnce of a cell? Can its value be greater than the emf of a cell? Explian.

Last Answer : What is terminal potential differnce of a cell? Can its value be greater than the emf of a ... C. being charged D. being either changed or discharged

Which of the following types of DC motors has its field connected in parallel with its armature? A. Counter EMF B. Shunt C. Salient pole D. Series

Description : Which of the following types of DC motors has its field connected in parallel with its armature? A. Counter EMF B. Shunt C. Salient pole D. Series

Last Answer : Answer: B

Why back emf used for a dc motor? highlight its significance.

Description : Why back emf used for a dc motor? highlight its significance.

Last Answer : The induced emf developed when the rotating conductors of the armature between the poles of magnet, in a DC motor, cut the magnetic flux, opposes the current flowing through the conductor, when the ... speed of rotation of the armature conductors. In starting, the value of back emf is zero.

Terminal potential difference of a battery is greater than its emf when a. the internal resistance of battery is infinite b. the internal resistance of battery is zero c. the battery is charged d. the battery is discharged

Description : Terminal potential difference of a battery is greater than its emf when a. the internal resistance of battery is infinite b. the internal resistance of battery is zero c. the battery is charged d. the battery is discharged

Last Answer : c. the battery is charged

The terminal voltage of a cell supplying energy to a circuit is usually less than its emf because of the cell's w) size x) internal resistance y) mass z) energy

Description : The terminal voltage of a cell supplying energy to a circuit is usually less than its emf because of the cell's w) size x) internal resistance y) mass z) energy

Last Answer : ANSWER: X -- INTERNAL RESISTANCE

Why the emf of a cell is always greater than its terminal voltage? Explain the same.

Description : Why the emf of a cell is always greater than its terminal voltage? Explain the same.

Last Answer : Every practical source offers some opposition to the current due to its internal parts or components. Such a resistance of internal parts of source is called internal resistance of source. When source delivers ... less than emf induced. So, emf of a cell is always greater than terminal voltage.

What is back emf in DC motor? Explain its significance.

Last Answer : Back emf: When the armature of DC motor rotates under the fixed magnetic field and cuts it, by Faraday's law an emf is induced in them. The induced emf acts in opposite direction to the ... the flow of armature current i.e. it automatically changes the armature current to meet load requirements.