What is Galvanometer: Definition and 56 Discussions
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely.
A galvanometer works by deflecting a pointer in response to an electric current flowing through a coil in a constant magnetic field. Galvanometers can be thought of as a kind of actuator.
Galvanometers came from the observation, first noted by Hans Christian Ørsted in 1820, that a magnetic compass's needle deflects when near a wire having electric current. They were the first instruments used to detect and measure small amounts of current. AndréMarie Ampère, who gave mathematical expression to Ørsted's discovery, named the instrument after the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk.
Galvanometers have been essential for the development of science and technology in many fields. For example, in the 1800s they enabled longrange communication through submarine cables, such as the earliest transatlantic telegraph cables, and were essential to discovering the electrical activity of the heart and brain, by their fine measurements of current.
Galvanometers have also been used as the display components of other kinds of analog meters (e.g., light meters and VU meters), capturing the outputs of these meters' sensors. Today, the main type of galvanometer still in use is the D'Arsonval/Weston type.
I know the torque will be zero when the deflection is zero and will be maximum when the angular displacement is θ0 but how to determine the exact shape of the graph?
Thanks
My guess is (c) since the rest of the options do not make sense to me but I am not sure about the shape of the graph.
Is (c) the correct answer? If yes, how to know whether the shape will be like in the option (straight line then curve downwards) or other shape like straight line only (like y =...
The present setup is a stepdown transformer.
Im thinking if n1 is decreased to match or be less than n2, then it will be a step up transformer.
so A.
(but answers say B)?
Hello guys.
I'm having some trouble to understand the real difference from the Galvanometer and the Ammeter.
The best comment I saw in some forum was:
Ammeter: ANY instrument used to measure electrical current
Voltimeter: ANY instrument used to measure voltage difference
Galvanometer: a...
Here is the problem
I have tried to draw the set up for both cases which the question had described above, and came to these 2 equations. But I can't see how it would help me to work out the resistance of the shunt?
Any help would be really great! Thanks
Homework Statement
[/B]
I am working on a experiment on finding the Earth's magnetic field strength in Denmark. Using a Galvanometer and a constant power source of 5.1V and slowly adjusting the resistance, I was able to find the changes in angle in relation to the changes of current.
2...
Homework Statement
If a shunt of 1/10th of the coil resistance is applied to a moving coil galvanometer,then it's sensitivity becomes
(a)10 fold
(b)11 fold
(c)1/10 fold
(d)1/11 foldHomework Equations
ϕ / I = NAB/LThe Attempt at a Solution
[/B]
So sensitivity gets increased by only these...
Homework Statement
A galvanometer of coil resistance 50.0 Ω deflects full scale for a current of 3.50 mA. What series resistance should be used with this galvanometer to construct a voltmeter which deflects full scale for 35.0 V
Homework Equations /Known Variables[/B]
R1 + R2... + Rn = Rtotal...
Homework Statement
galvanometer with 50 divisions on the scale requires a current sensitivity of 0.1 m A/division. The resistance of the galvanometer is 40Ω. If a shunt resistance 0.1 Ω is connected across it, find the maximum value of the current that can be measured using this ammeter...
Homework Statement
A galvanometer is connected to a solenoid, and there is a magnet bar entering the solenoid to induce an emf. What factors determine the displacement of the pointer of the galvanometer?
Homework Equations
emf (induced) = N ΔΦ/ Δt
sensitivity of the galvanometer = θ/i
The...
Homework Statement
Homework Equations
sensitivity= θ/i
The Attempt at a Solution
That's the answer in my textbook:
Sensitivity = θ/i = 60/30 = 2 deg/mA
But I wonder why it used the angle 60 (the angle between the coil face and the field lines) instead of the angle 30 (the angle between the...
Homework Statement
In order to provide full scale deflection the coil current required in a galvanometer is 190μA and the resistance of the coil in the galvanometer is 35Ω
 What is the value of the resistor to be connected in parallel with the meter so that full scale deflection is obtained...
Homework Statement
(a) What is meant by the statement that a solenoid has an inductance of 2.0 H?
A 2.0 H solenoid is connected in series with a resistor, so that the total resistance is 0.50 Ω, to a 2.0 V DC supply. Sketh the graph of current against time when the crrent is switched on.
What...
Homework Statement
(a) A movingcoil galvanometer consists of a rectangular coil of N turns each of area A suspended in a radial magnetic field of flux density B. Derive an expression for the torque on the coil when a current I passes through it. (You may assume the expression for the force on...
Homework Statement
A square coil of side a and consisting of N turns is free to rotate about a vertical axis through the midpoints of two opposite sides. It is situated in a uniform horizontal magnetic field of flux density B so that the plane of the coil makes an angle θ with the field. Draw...
My question is : What is the absolute capacitance?In my electricity lab, I was assigned to prepare a report on measuring absolute capacitance of a capacitor using ballistic galvanometer.
I am familiar to the term self capacitance but not the absolute one. My mentor asked me to find it out by...
When no current is passed through the coil it shows no deflection i.e. B is in the direction shown. But according to theory both fields should be perpendicular (Earth's horizontal field and the one due to coil).
But I am confused because the coil would ideally create a magnetic field that is...
I am trying to convert galvanometer into an ammeter. But after finding Galvanometer resistance and shunt values, and cut a wire according to that thickness and connected. But still, the galavanometer reading is not similar to that of the standard ammeter reading connected in the circuit. Any one...
Homework Statement
Zero deflection in galvanometer
Homework Equations
If potential difference across between two points between which galvanometer is kept is zero galvanometer shows zero deflection.
The Attempt at a Solution
But my doubt starts from this video at 3:33 to 3:44 teacher says...
Homework Statement
when the balance point is achieved , there're no current passing thru , so Galvanometer should show 0 . Am i right... so there's no current passing thru the 20 ohm resistor . so my working is ( 8.1/120 )(40) = 2.7 V ...
correct me if I'm wrong...Homework EquationsThe Attempt...
A galvanometer of coil resistance 50 Ω deflects full scale for a current of 3.50mA. What series resistance should be used with this galvanometer to construct a voltmeter which deflects full scale for 35.0 V ?
r=50 Ω I=3.50mA=0.0035 V=35.0v R=?
I= V/R
The Attempt at a...
To make ammeter,
Resistance of proper small value is joined in parallel to the coil of galvanometer.This resistance is called a shunt.
For smaller resistance value,
We can not use the smallest resistance wire that is directly wound on coil of galvanometer so the resistance will become...
Dear All,
I have a doubt whether galvanometer detects displacement currents due to time varying electric field or not?please let me know,if anybody have an idea about this.
Regards
Arvind
Homework Statement
how will you convert a galvanometer of resistance 150 ohm giving a full scale deflection for a current of 3 milli ampere to a ammeter of range 0 to 6 ampere?a uniform rsistance wire of length 60cm and 2 ohm is given.find the length of the wire required?
Homework...
In a galvanometer the magnetic poles are cut in such a fashion which ensures radial magnetic field. If field is radial then the angle between magnetic moment i.e Area vector of the coil and field is zero. Thus the coil should not experience any torque when current is passed through the coil...
How will you convert a galvanometer of resistance 12 ohms showing full scale deflection for a current of 3 milli ampere to
(i) Ammeter of range o to 6 Ampere
(ii) Voltmeter of range 0 to 18V.
Hello, just been reading a little bit about the basics of moving coil meter and one thing is bugging me.
First if we have a basic square looped coil in and uniform magnetic field. There is torque ( m x B ) due to the magnetic field and then there is the system/spring attached to the coil...
In which direction will the pointer move when current is passed?
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[Galvanometer]
Does it move to the right?
AND
There is another one that is connected from top to bottom:


^



() [Galvanometer]



^



Where will the () move?
This is kind of a stupid question but...to measure high currents, a galvanometer is connected parallel to a shunt resistance so that most of the current passes through the shunt resistance but only a small amount of current passes through the galvanometer. But wouldn't this defeat the purpose of...
i have problem to conceptualize this old galvanometer readings for voltage drop. i plot a diagram of circuit of interest for bether explanation of what's bothering me.
so, in DC circuit with some resistor in series, electric current is constant and is of some known value. and if i want to use...
A galvanometer has a full scale current of 0.100 mA and a coil resistance of 50ohmes. In constructing an ammeter of 60mA full scale, what shunt resistnace is needed?I'm lost on this one.
Homework Statement
The resistance of a galvanometer coil is 25ohms and the current required for full scale deflection is 500μA.
a) explain how to convert the galvanometer to an ammeter reading 20mA full scale, and compute the shunt resistance
b) explain how to convert the galvanometer to a...
I have set up an apparatus to find the Null point with a galvanometer. I am unable to find one as the galvanometer always points to the right, no matter what. Help anyone?
Homework Statement
a movingcoil gavanometer consists of a coil that is free to rotate between the poles of a permanent magnet. the magnetic field strength between the poles is 5 x (10^2) T. The coil consists of 250 loops of copper wire, diameter 0.5 mm, wound to form a square coil, with an...
I had this doubt for over 1 year! I thought of asking about it here.
In the conversion of a galvanometer to an ammeter by connecting a shunt in parallel to the galvanometer, maximum amount of current flows through the shunt because it has a very very low resistance. In other words, very less...
hey I've been snooping around trying to find out who invented the D'Arsonval/Weston galvanometer movement? I am not able to find it or in other words I am getting different sources from different web?..
so who invented the D'Arsonval/Weston galvanometer movement.?
Homework Statement
a galvanometer with 50 divisions on the scale requires a current sensitivity of 0.1 m A/division. find the galvanometer current?
Homework Equations
IS= \theta/I
TO find the galvanometer current, i multiplied 50 with 0.1 to get the galvanometer current, as instructed...
What I had to do for a physics prac was to create a tangent galvanometer using this like...square piece of wood and a flat piece of wood in the middle... and we put a compass in the middle and increased the number of coils (carrying current) and recorded the deflection made by the compass and...
suppose you have a solenoid with hollow core connected to a galvanometer.
On one side you have a SN magnet (ie. the N pole is nearer to the solenoid). On the other side you have a NS magnet( ie. S pole is nearer to solenoid). ie.
[S  N] [Solenoid] [N  S]
Both magnets are...
[SOLVED] Direct Current Circuit with Galvanometer.
Homework Statement
http://img299.imageshack.us/img299/6357/document002aa5.jpg
Homework Equations
V = IR
The Attempt at a Solution
http://img263.imageshack.us/img263/6684/document003kl5.jpg
I did the following but the...
part 1: A galvanometer has a coil with a resistance of 81 W. A current of 131 mA causes full scale deflection. Calculate the value of the series resistor that is required in order to use the galvanometer as a Voltmeter with 40 V full scale.
so to make a voltmeter, the galvanometer and...
Homework Statement
1) A capacitor of capacity 3 micro farad charged by a potential of 2 volt when discharged through a Ballistic galvanometer gives a deflection of 24 divisions. Determine the sensitivity of the Ballistic galvanometer.
Homework Equations
The Attempt at a Solution...
hey all,
ill start you off with what I am trying to make here... I am tryting to make a galvanometer.. 2D.
I am trying to make a galvanometer so i can bounce a laser off a mirror mounted on it. then use the mirror to create laser patterns.
first of all, does anybody know where i...
A galvanometer of coil resistance 50 ohms deflects full scale for a current of 3.5 mA. What series resistance should be used with this galvanometer to construct a voltmeter which deflects full scale for 35 Volts?
A galvanometer of 90 ohms internal resistance has a fullscale current of 350. microA. Describe how to use this meter to make : (a) a 150 V voltmeter, and (b) a 10.0A ammeter
So (a) Resistors must be connected in series with the galvanometer, R=4.29 x 10^5 ohms.
(b) A shunt resistor must...
Hello all. I would like to measure the tension on a very thin magnet wire and I have read about people making scales with a galvanometer (voltmeter). Basically, instead of using the meter to measure current, you send current thru the galvanometer and use the needle to exert force on an object...
I know that the pointer of the galvanometer makes use of the turning effect to indicate the strength of the current. Say, the pointer is moved to the position of 8mA, if the current is suddenly withdrawn, the pointer would be pointing back to zero. What's the mechanism behind this?