Using Galvanometer of 90 Ohms Resistance for 150V Voltmeter & 10A Ammeter

[lilkrazyrae]

A galvanometer of 90 ohms internal resistance has a full-scale 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 be used in parallel with the galvanometer. :rofl:

 

[Andrew Mason]

A galvanometer of 90 ohms internal resistance has a full-scale 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 be used in parallel with the galvanometer. :rofl:

Find the voltage required to give the galvanometer coil full deflection and then figure out what resistor carrying 10 amps of current will provide that voltage drop. That resistor placed in parallel with the galvanometer will be a 10 amp ammeter.

AM

 

[kyle8921]

To use this galvanometer as a 150V voltmeter, we would need to connect a series resistor with a resistance of 4.29 x 10^5 ohms. This will create a voltage divider circuit, where the voltage across the galvanometer will be proportional to the voltage across the entire circuit. By using this setup, we can calculate the voltage across the galvanometer using the formula Vg = (Rg/(Rg+Rs)) x Vtotal, where Vg is the voltage across the galvanometer, Rg is the internal resistance of the galvanometer, Rs is the series resistor, and Vtotal is the total voltage across the circuit. By setting Rs to be 4.29 x 10^5 ohms, we can ensure that the voltage across the galvanometer will be 150V when the full-scale current of 350 microA is passing through it.

To use this galvanometer as a 10.0A ammeter, we would need to connect a shunt resistor in parallel with the galvanometer. The shunt resistor should have a resistance of 0.2571 ohms, calculated using the formula Rs = Rg x (Ig/I - 1), where Rs is the shunt resistor, Rg is the internal resistance of the galvanometer, Ig is the full-scale current of the galvanometer, and I is the desired current to be measured. By connecting the shunt resistor in parallel with the galvanometer, the majority of the current will pass through the shunt resistor, while a small portion will pass through the galvanometer. This will allow us to measure the current through the galvanometer using the formula Ig = (I x Rg)/(Rg + Rs). By setting Rs to be 0.2571 ohms and using a 10.0A current, we can ensure that the full-scale current of the galvanometer will be 350 microA.

 

[quicknote]

To create a 150 V voltmeter, the galvanometer must be connected in series with a resistor of 4.29 x 10^5 ohms. This will create a voltage divider circuit, with the galvanometer and resistor acting as two resistances in series. By measuring the voltage drop across the galvanometer, the voltage across the entire circuit can be calculated using Ohm's law.

To create a 10.0A ammeter, a shunt resistor must be connected in parallel with the galvanometer. The shunt resistor should have a resistance of 9 x 10^-3 ohms. This will allow most of the current to flow through the shunt resistor, while a small portion will continue through the galvanometer. By measuring the current through the galvanometer, the total current in the circuit can be calculated using Ohm's law.