Permanent Magnet Moving Coil (PMMC) Instrument

Permanent Magnet Moving Coil (PMMC) Instrument
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Permanent Magnet Moving Coil (PMMC) Instrument.png

Permanent Magnet Moving Coil (PMMC) Instrument

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Answer :

Permanent Magnet Moving Coil (PMMC) Instrument

Permanent Magnet Moving Coil (PMMC) Instrument.png
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Related questions

Name the material used for :- (i) Moving coil (ii) Permanent magnet in PMMC instrument.

Description : Name the material used for :- (i) Moving coil (ii) Permanent magnet in PMMC instrument.

Last Answer : (i) Material used for Moving coil: Copper, Aluminum( some times)  (ii) Permanent magnets are made of special alloys such as :  Aluminum-Nickel-Cobalt (Alnicos)  Strontium-Iron  Neodymium-Iron-Boron  Samarium-Cobalt.

The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : -

Description :  The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : - a) weaking of the permanent magnet due to aging at temperature effects b) weaking of spring due to aging and temperature effects c) change of resistance of the moving coil with temperature d) all the above

Last Answer :  The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : - a) weaking of the permanent magnet due to aging at temperature effects b) weaking of spring due to aging and temperature effects c) change of resistance of the moving coil with temperature d) all the above

Permanent-magnet moving coil instrument can be used in

Description : Permanent-magnet moving coil instrument can be used in

Last Answer : dc work only

What is the reason why the scale of a permanent-magnet moving coil instrument is uniform?

Description : What is the reason why the scale of a permanent-magnet moving coil instrument is uniform?

Last Answer : because it is spring controlled

A permanent magnet moving coil instrument gives full scale deflection of 25mA when a voltage of 75mV is applied across it. Calculate: (i) Resistance of shunt required for full scale deflection of 150 A. (ii) Series resistance for full scale deflection of 500 V.

Description : A permanent magnet moving coil instrument gives full scale deflection of 25mA when a voltage of 75mV is applied across it. Calculate: (i) Resistance of shunt required for full scale deflection of 150 A. (ii) Series resistance for full scale deflection of 500 V.

Last Answer : Answer :

A moving-coil permanent-magnet instrument can be used as flux-meter?

Last Answer : A moving-coil permanent-magnet instrument can be used as flux-meter by eliminating the control springs.

A moving-coil permanent-magnet instrument can be used as what by using a low resistance shunt?

Last Answer : A moving-coil permanent-magnet instrument can be used as ammeter by using a low resistance shunt.

Which of the following electric meter movements uses a stationary permanent magnet and movable coil? A. D'Arsonval B. Electrodynamometer C. Moving iron-vane D. Inclined coil iron-vane

Description : Which of the following electric meter movements uses a stationary permanent magnet and movable coil? A. D'Arsonval B. Electrodynamometer C. Moving iron-vane D. Inclined coil iron-vane

Last Answer : Answer: A

A permanent magnet moving coil ammeter has a coil resistance of 99 ohm and Full Scale Deflection (FSD)

Description : A permanent magnet moving coil ammeter has a coil resistance of 99 ohm and Full Scale Deflection (FSD) current of 0.1mA. Shunt resistance is 1 ohm. Current through the meter at 0.5 F.S.D is:

Last Answer : A permanent magnet moving coil ammeter has a coil resistance of 99 ohm and Full Scale Deflection (FSD) current of 0.1mA. Shunt resistance is 1 ohm. Current through the meter at 0.5 F.S.D is: 0.05mA

Permanent magnet moving coil instruments are used for

Description : Permanent magnet moving coil instruments are used for

Last Answer : PMME are mostly used for measuring voltage and current.

A PMMC instrument has FSD of 100 μA and a coil resistance of 1 kΩ. To convert the instrument into an

Description : A PMMC instrument has FSD of 100 μA and a coil resistance of 1 kΩ. To convert the instrument into an ammeter with full scale deflection of 100 mA, the required shunt resistance is (A) 1 Ω (B) 1.001 Ω (C) 0.5 Ω (D) 10 Ω

Last Answer : A PMMC instrument has FSD of 100 μA and a coil resistance of 1 kΩ. To convert the instrument into an ammeter with full scale deflection of 100 mA, the required shunt resistance is 1.001 Ω

State the material used for moving coil and former for PMMC instruments.

Description : State the material used for moving coil and former for PMMC instruments. 

Last Answer : Material Used for Moving Coil and Former for PMMC Instruments:  Material used for moving coil: Copper  Material used for Former: Aluminium

Magnetic flux linked with a coil can be changed by using an: a. Permanent magnet b.Bar magnet c. Electromagnet d. Horseshoe magnet

Description : Magnetic flux linked with a coil can be changed by using an: a. Permanent magnet b.Bar magnet c. Electromagnet d. Horseshoe magnet

Last Answer : b.Bar magne

The pole faces of U-shaped magnet in a moving coil galvanometer are made concave to a) decrease the strength of magnetic field b) create a non-uniform magnetic field c) make the magnetic field radial d) All of these

Description : The pole faces of U-shaped magnet in a moving coil galvanometer are made concave to a) decrease the strength of magnetic field b) create a non-uniform magnetic field c) make the magnetic field radial d) All of these

Last Answer : c) make the magnetic field radial

Basically, a PMMC instrument can be used only in

Description : Basically, a PMMC instrument can be used only in

Last Answer : dc measurements

Another name for PMMC instrument

Description : Another name for PMMC instrument

Last Answer : D'Arsonval

Derive the relation for deflection torque in PMMC instrument.

Description : Derive the relation for deflection torque in PMMC instrument. 

Last Answer : Ans: The length of coil be l meter and width of coil be d meter. Assume I is the current flowing in the ciol having N turns. Assume B as the flux density in the air gap then F=BIL ... a direct indication of the current in the coil. The pointer deflection can therefore be used to measure current.

Draw the diagram of PMMC instrument and state the deflection torque equation

Description : Draw the diagram of PMMC instrument and state the deflection torque equation

Last Answer : Equation Ʈ= B*A*I*N Where r= torque Newton. Meter B = flux density in the air gap. Wb/m2 A = effective coil area (m) N= number of turns of wire of the coil

List two advantages of PMMC instrument.

Description : List two advantages of PMMC instrument.

Last Answer : 1. It has uniform scale. 2. Power consumption is low 3. It can be obtained in wide ranges. 4. High sensitivity & accuracy 5. It is unaffected by external magnetic field. 6. Additional damping device not required. 7. Hysteresis problem is not there.

State the working principle of PMMC Analog instrument.

Description : State the working principle of PMMC Analog instrument.

Last Answer : Working Principal of PMMC Analog Instrument: When current carrying conductor is placed in a magnetic field, it experiences mechanical force. In PMMC instrument, when current flows through a coil ... coil rotates and pointer attached to the coil shows deflection proportional to the current magnitude.

feature of PMMC instrument.

Description : feature of PMMC instrument. 

Last Answer : Consumes less power Great accuracy. High torque to weight ratio

State the function of former and control spring in PMMC instrument.

Description : State the function of former and control spring in PMMC instrument.

Last Answer : Function of Former: To support the coil and provide eddy current damping.  Function of Control Spring: To provide control torque or force and in some instruments springs can be used as current leads.

‘PMMC instrument is not suitable to measure AC quantity’. State the reason.

Description : ‘PMMC instrument is not suitable to measure AC quantity’. State the reason.

Last Answer : The direction of force exerted on moving coil depends on the direction of current flowing through moving coil. If the direction of magnetic field is kept constant, it produces unidirectional torque if the current is ... on the coil in one cycle to zero. Hence the meter cannot read A.C. quantities.

State working principle of PMMC instrument.

Description : State working principle of PMMC instrument.

Last Answer : Working Principle of PMMC Instrument: When current carrying conductor is placed in a constant magnetic field, it experiences a force proportional to the current and produces proportional deflection torque. 

Compare PMMC & MI instrument.

Description : Compare PMMC & MI instrument.

Last Answer : MI Instrument  PMMC Instrument  It works on the principles of magnetism.  It works on the principle of DC motor Deflection torque is proportional to square of current  Deflection ... , Voltmeter and Watt meter  Can be used as voltmeter, Ammeter, Galvanometer, ohmmeter  

Which of the following factors limit the deflection of the pointer of a PMMC instrument of about

Description : Which of the following factors limit the deflection of the pointer of a PMMC instrument of about 90o?  1. Its damping mechanism  2. Linearity of magnetic field in which the coil moves  3. Control spring arrangement  4. ... Only 1 and 3 (b) Only 2 and 4 (c) Only 2 and 3 (d) Only 1 and 4 

Last Answer : Which of the following factors limit the deflection of the pointer of a PMMC instrument of about 90o?  1. Its damping mechanism  2. Linearity of magnetic field in which the coil moves  3. Control spring arrangement  4. ... Only 1 and 3 (b) Only 2 and 4 (c) Only 2 and 3 (d) Only 1 and 4 

In a PMMC instrument, the damping provided is :

Description : In a PMMC instrument, the damping provided is :  (A) air damping (C) eddy current damping (B) fluid damping (D) magnetic damping using a magnet

Last Answer : In a PMMC instrument, the damping provided is : eddy current damping 

PMMC instrument gives uniform scale because:

Description : PMMC instrument gives uniform scale because:

Last Answer : PMMC instrument gives uniform scale because: It uses spring control and The deflection torque is proportional to the instrument current.

A PMMC instrument can be used as a fluxmeter by:

Last Answer : A PMMC instrument can be used as a fluxmeter by: Removing the control spring

Explain the construction and working of moving coil instrument.

Description : Explain the construction and working of moving coil instrument.

Last Answer : Construction: The moving part is a coil wound on a light aluminium frame, mounted on a shaft made of stainless steel which is pivoted at either ends on jewel bearing made of sapphire. The coil is placed between ... . Where B is magnetic flux, N is number of turns and L is length of coil. 

Current range extension in moving coil instruments can be achieved by placing a ___ in shunt with the instrument.

Description : Current range extension in moving coil instruments can be achieved by placing a ___ in shunt with the instrument.

Last Answer : low resistance resistor

What is the typical full-scale deflection current of a moving coil instrument?

Description : What is the typical full-scale deflection current of a moving coil instrument?

Last Answer : 50mA

A moving coil instrument has a resistance of 10 W and gives full scale deflection when carrying

Description : A moving coil instrument has a resistance of 10 W and gives full scale deflection when carrying a current of 50 mA. To measure current upto 100 A, we will have to connect • 10 W resistance in series • 10 W resistance in parallel • 10/1999 W resistance in series • 10/1999 W resistance in parallel

Last Answer : A moving coil instrument has a resistance of 10 W and gives full scale deflection when carrying a current of 50 mA. To measure current upto 100 A, we will have to connect 10/1999 W resistance in parallel

A moving coil instrument of resistance 5 Ohm requires a potential difference of 75 mV to give a full scale...

Description : A moving coil instrument of resistance 5 Ohm requires a potential difference of 75 mV to give a full scale deflection. The value of shunt resistance needed to give a full scale deflection at 30 A is

Last Answer : A moving coil instrument of resistance 5 Ohm requires a potential difference of 75 mV to give a full scale deflection. The value of shunt resistance needed to give a full scale deflection at 30 A is 2.5 milliOhm

In a moving coil instrument, the deflecting torque is proportional to

Last Answer :  In a moving coil instrument, the deflecting torque is proportional to Current.

A moving coil instrument is used as an ohmmeter. The indicating scale of the meter will be

Last Answer : A moving coil instrument is used as an ohmmeter. The indicating scale of the meter will be Hyperbolic.

In a dynamo-meter type of moving coil instrument a swamping resistance is provided in order to:

Last Answer : In a dynamo-meter type of moving coil instrument a swamping resistance is provided inorder to: Provide equal time constant for moving coil and fixed coil, when used for ac measurement

Which of the following instruments have least torque/weight ratio: a) Dynamometer type b) PMMC c) Attraction type moving iron d) Repulsion type moving iron

Description : Which of the following instruments have least torque/weight ratio: a) Dynamometer type b) PMMC c) Attraction type moving iron d) Repulsion type moving iron

Last Answer : Ans: A

Moving iron and PMMC instruments can be distinguished from each other by looking at:

Last Answer : Moving iron and PMMC instruments can be distinguished from each other by looking at: Scale

The pole pieces of the magnet used in a pivoted coil galvanometer are

Description : The pole pieces of the magnet used in a pivoted coil galvanometer are

Last Answer : The pole pieces of the magnet used in a pivoted coil galvanometer are A. plane surfaces of a ... magnet D. cylindrical sufaces of a horse-shoe magnet

Give reason: Stationary coil and stationary magnet cannot produce induced electric current.

Description : Give reason: Stationary coil and stationary magnet cannot produce induced electric current.

Last Answer : An emf is induced in the coil only when there is relative motion between the coil and the magnet.

Can a static magnet induce an e.m.f in a stationary coil of wire? Give reasons.

Description : Can a static magnet induce an e.m.f in a stationary coil of wire? Give reasons.

Last Answer : No, when both coil and magnet are stationary, the magnetic field linked with the coil remains constant. Only when the magnetic field linked with the coil changes, current is produced.

Induced current in coil by a magnet turns it into an A. straight wire B. magnet C. ammeter D. electromagnet

Description : Induced current in coil by a magnet turns it into an A. straight wire B. magnet C. ammeter D. electromagnet

Last Answer : electromagnet

By accelerating the magnet inside the coil, the current in it A. increases B. decreases C. remains constant D. reverses

Description : By accelerating the magnet inside the coil, the current in it A. increases B. decreases C. remains constant D. reverses

Last Answer : increases

How can electric currents be induced with a coil and a magnet?

Description : How can electric currents be induced with a coil and a magnet?

Last Answer : by moving either the magnet or the coil

Which component is mainly used in a DC generator: a.slip ring b. commutator c. magnet d. coil

Description : Which component is mainly used in a DC generator: a.slip ring b. commutator c. magnet d. coil

Last Answer : b. commutator

The series magnet of a single phase Energy meter consists of coil of _____.

Last Answer : The series magnet of a single phase Energy meter consists of coil of thick wire of few turns.

When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon

Last Answer : When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon resistance of the coil.

Is the idea of permanent magnet "free energy" generators impossible?

Description : Is the idea of permanent magnet "free energy" generators impossible?

Last Answer : answer:It's hard to say. I've tried building a few myself with no avail. I have gotten close a few times though, and that's just tinkering around. The problem with permanent magnets in a ... com/watch?v=bssBAb6EzM4&feature=related This one looks like it works, but was later revealed to be a hoax.

What does a permanent magnet repel? -Do You Know?

Description : What does a permanent magnet repel? -Do You Know?

Last Answer : answer: