- #1
dgresch
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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.
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How to Calculate Shunt Resistance for Converting a Galvanometer to an Ammeter?
- Thread starter dgresch
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- Ammeter Galvanometer
In summary, to construct an ammeter with a full scale current of 60mA, a shunt resistance of 0.083ohms is needed. This can be calculated using the formula s=(Ig/(I-Ig))*R, where s is the required shunt, R is the resistance of the galvanometer (50ohms), Ig is the full scale deflection current of the galvanometer (0.1mA), and I is the desired current range (60mA).
- #2
gneill
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This is a common problem type. Try searching the forum for similar examples. In fact, take a look at the bottom of this window under the "Similar Threads" header.
- #3
berkeman
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dgresch said:
You want 0.1mA to go through the 50 Ohm coil, and the rest of the 60mA to go through the low-resistance shunt in parallel with the coil. What do you think the Relevant Equations are?
- #4
dgresch
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Thanks gneill, I'm new to this and I thought to just post my own thread since I didn't see it on google :P.
- #5
rohans
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is the answer 0.083ohm
- #6
gneill
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rohans said:
It might be
Can you show your work?- #7
rohans
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s=(Ig/(I-Ig))*R
s-required shunt
R-resistance of galvanometer(50)
Ig-full scale deflection current of the galvanometer(0.1)
I-desired current range(60)
just substitute the given data
s-required shunt
R-resistance of galvanometer(50)
Ig-full scale deflection current of the galvanometer(0.1)
I-desired current range(60)
just substitute the given data
1. How does a galvanometer work?
A galvanometer works by using a coil of wire suspended between two magnets. When an electric current flows through the coil, it produces a magnetic field that interacts with the magnets, causing the coil to rotate.
2. What is the purpose of a galvanometer?
The purpose of a galvanometer is to measure small electric currents. It can also be used as a sensitive voltmeter or as a part of a larger instrument, such as an ammeter or oscilloscope.
3. How does a galvanometer become an ammeter?
A galvanometer can be converted into an ammeter by adding a shunt resistor in parallel with the coil. This allows only a small portion of the current to pass through the coil, while the majority of the current flows through the shunt resistor and is measured as the ammeter reading.
4. What is the difference between a galvanometer and an ammeter?
The main difference between a galvanometer and an ammeter is their sensitivity. A galvanometer is more sensitive and can measure smaller currents, while an ammeter is less sensitive and can measure larger currents. Additionally, an ammeter has a lower resistance than a galvanometer, allowing it to measure the current without significantly affecting it.
5. How accurate are galvanometer and ammeter readings?
The accuracy of galvanometer and ammeter readings depends on various factors, such as the quality of the instrument and the skill of the operator. However, with proper calibration and use, both can provide accurate readings within a certain range. It is important to regularly calibrate and maintain these instruments for optimal accuracy.
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