A GALVANOMETER WITH COIL RESISTANCE 12.0OHMS SHOWS FULL SCALE DEFLECTION FOR A CURRENT OF 2.5MA HOW WOULD YOU CONVERT IT INTO A VOLTMETER OF RANGE 0 TO 10VOLTS
Add a resistor in series with the
coil:
R+12 = E/I = 10/0.0025 = 4,000,
R = 4,000-12 = 3,988 Ohms.
R = (10-0.0025*12)/0.0025 = 9.97/0.0025 = 3,988 Ohms.
To convert the given galvanometer into a voltmeter with a range of 0 to 10 volts, we can use a shunt resistor.
Here's how you can calculate the value of the shunt resistor:
1. Determine the desired full scale deflection current of the voltmeter.
Let's assume we want a full scale deflection of 10 volts, so the current corresponding to this will be the same as the current that caused full scale deflection in the galvanometer, which is 2.5 mA.
2. Calculate the current through the shunt resistor.
The current through the shunt resistor should be equal to the current required for full scale deflection of the voltmeter. In this case, it will be 2.5 mA.
3. Calculate the resistance of the shunt resistor.
The formula to calculate the resistance of the shunt resistor is:
Rshunt = (Rg × (Ig – Iv)) / Iv
Where:
Rshunt is the resistance of the shunt resistor,
Rg is the resistance of the galvanometer (12.0 ohms),
Ig is the current that caused full scale deflection in the galvanometer (2.5 mA),
and Iv is the desired full scale deflection current of the voltmeter (2.5 mA).
Rshunt = (12.0 ohms × (2.5 mA - 2.5 mA)) / 2.5 mA
= 0 ohms
Based on the calculation, the resistance of the shunt resistor required is 0 ohms, which means a direct connection is needed from the galvanometer to measure the desired voltage range of 0 to 10 volts.
To convert a galvanometer into a voltmeter with a specific range, you will need to add a shunt resistor in parallel with the galvanometer.
First, let's determine the current that flows through the galvanometer for full scale deflection. In this case, the current is given as 2.5mA.
Next, we need to calculate the resistance of the shunt resistor required to achieve the desired voltage range of 0 to 10 volts. The resistance of the shunt resistor can be calculated using Ohm's Law:
R_shunt = (V_range) / (I_full_scale)
where R_shunt is the resistance of the shunt resistor, V_range is the desired voltage range (10 volts), and I_full_scale is the full scale deflection current (2.5mA).
R_shunt = 10 V / 2.5 mA = 10 V / 0.0025 A = 4000 ohms
Therefore, a shunt resistor with a resistance of 4000 ohms is required.
To convert the galvanometer into a voltmeter, you need to connect the shunt resistor in parallel with the galvanometer. The positive terminal of the galvanometer should be connected to the positive terminal of the shunt resistor, and the negative terminals of both components should be connected together.
When the current flows through the circuit, most of it will pass through the shunt resistor, and only a small fraction will flow through the galvanometer. The voltage across the shunt resistor can then be measured to determine the voltage across the entire circuit.
By adjusting the resistance value of the shunt resistor, you can calibrate the voltmeter to have the desired voltage range.