Electric meter task
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- Jack, Can you help me? I forgot to learn about electric meters
- Okay so first, how does a simple moving-coil galvanometer work?
- Oh sure, ask away Ben
- Oh okay. For the second, how does a moving-coil galvanometer can be modified for use as an ammeter AND a voltmeter
- A moving coil galvanometer works on the principle that a current-carrying coil placed in a magnetic field, experiences a torque. The coil springs along with the radial field ensure the deflection to be proportional to the strength of the current.
- A galvanometer can be converted into an ammeter by connecting a shunt resistance in parallel to it. The shunt resistance should have very low resistance. A moving-coil galvanometer can be converted into a voltmeter by increasing its effective resistance by connecting a high resistance Rs in series with the galvanometer.
- You will need to take notes Ben
- Okay, I got it. For the last one, why an ammeter should have a very low resistance AND a voltmeter should have a very high resistance
- The series resistance protects the meter and increases the range of the meter. This gives the required value of the series resistance.
- Okay. Thank you for your help
- The ammeter should have low resistance because because its measuring the current that is coming in the circuit. The voltmeter should have very high resistance because it measures the current on the opposite sides of a resistor.
- Oh yeah, same. Anyways, thanks again for your help
- Your welcome Ben
- No problem. I got to go now, class is starting.
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