What is the use of galvanometer as voltmeter and ammeter?
2 Answers
A galvanometer is a sensitive instrument that measures small electric currents. When used as a voltmeter or ammeter, it is modified in specific ways to extend its range and functionality.
### Galvanometer as a Voltmeter:
1. **Configuration**: A galvanometer can be converted into a voltmeter by connecting a high resistance (shunt resistor) in series with it.
2. **Function**: This allows the galvanometer to measure voltage across a circuit. The high resistance ensures that only a small fraction of the current flows through the galvanometer, preventing damage and enabling the measurement of higher voltages.
3. **Calibration**: The scale of the galvanometer is calibrated to read voltage directly, based on the relationship between current, resistance, and voltage (Ohm's Law).
### Galvanometer as an Ammeter:
1. **Configuration**: To use a galvanometer as an ammeter, a low resistance (shunt resistor) is connected in parallel with it.
2. **Function**: This configuration allows most of the current to pass through the shunt while a small portion passes through the galvanometer. This enables the measurement of larger currents without damaging the instrument.
3. **Calibration**: The galvanometer is calibrated to read current directly, reflecting the total current in the circuit based on the proportion of current flowing through the galvanometer versus the shunt.
### Summary:
- **Voltmeter**: High resistance in series, measures voltage.
- **Ammeter**: Low resistance in parallel, measures current.
Both configurations leverage the galvanometer's sensitivity, allowing it to function effectively across different ranges of voltage and current.
### Galvanometer as a Voltmeter:
1. **Configuration**: A galvanometer can be converted into a voltmeter by connecting a high resistance (shunt resistor) in series with it.
2. **Function**: This allows the galvanometer to measure voltage across a circuit. The high resistance ensures that only a small fraction of the current flows through the galvanometer, preventing damage and enabling the measurement of higher voltages.
3. **Calibration**: The scale of the galvanometer is calibrated to read voltage directly, based on the relationship between current, resistance, and voltage (Ohm's Law).
### Galvanometer as an Ammeter:
1. **Configuration**: To use a galvanometer as an ammeter, a low resistance (shunt resistor) is connected in parallel with it.
2. **Function**: This configuration allows most of the current to pass through the shunt while a small portion passes through the galvanometer. This enables the measurement of larger currents without damaging the instrument.
3. **Calibration**: The galvanometer is calibrated to read current directly, reflecting the total current in the circuit based on the proportion of current flowing through the galvanometer versus the shunt.
### Summary:
- **Voltmeter**: High resistance in series, measures voltage.
- **Ammeter**: Low resistance in parallel, measures current.
Both configurations leverage the galvanometer's sensitivity, allowing it to function effectively across different ranges of voltage and current.
A galvanometer is an instrument used to detect and measure small electric currents. It operates on the principle of electromagnetic induction, where a magnetic field interacts with a coil of wire, causing it to deflect. This deflection can be calibrated to indicate the strength of the current. Galvanometers can be adapted for use as voltmeters and ammeters, which are devices used to measure voltage and current, respectively. Here's how each adaptation works:
### Galvanometer as a Voltmeter
1. **Basic Principle**: A galvanometer can be converted into a voltmeter by using it to measure the potential difference (voltage) across a component in a circuit.
2. **Modification**: To use a galvanometer as a voltmeter, a high-resistance resistor, called a **shunt resistor**, is connected in series with the galvanometer. This arrangement ensures that most of the voltage is dropped across the shunt resistor, allowing only a small portion to pass through the galvanometer.
3. **Calibration**: The voltmeter is calibrated by applying known voltage levels and recording the galvanometer’s deflection. This allows the scale on the voltmeter to be marked with appropriate voltage values corresponding to the galvanometer’s deflection.
4. **Operation**: When a voltage is applied, the current that flows through the circuit causes the galvanometer needle to move. The degree of movement indicates the voltage, with a scale providing a direct reading.
5. **Sensitivity**: The high resistance of the series resistor allows the voltmeter to measure high voltages without drawing significant current, which could affect the circuit being measured.
### Galvanometer as an Ammeter
1. **Basic Principle**: A galvanometer can also be used to measure current by allowing the current to pass through the instrument directly.
2. **Modification**: To convert a galvanometer into an ammeter, a low-resistance resistor, known as a **shunt resistor**, is placed in parallel with the galvanometer. This configuration allows most of the current to bypass the galvanometer while a small fraction flows through it.
3. **Calibration**: The ammeter is calibrated similarly by passing known currents through the circuit and recording the corresponding deflections of the galvanometer. The scale is then marked with the current values.
4. **Operation**: When current flows through the circuit, the small portion that passes through the galvanometer causes the needle to deflect. The deflection indicates the current in the circuit, with the scale providing a direct reading.
5. **Range Extension**: By changing the value of the shunt resistor, the ammeter can be adapted to measure different ranges of current, from small to large values, without damaging the galvanometer.
### Summary
- **Voltmeter**: Measures voltage by using a high-resistance series resistor to protect the galvanometer. It shows the potential difference across a component.
- **Ammeter**: Measures current by using a low-resistance parallel shunt resistor, allowing most current to bypass the galvanometer. It shows the current flowing through the circuit.
By modifying a galvanometer with appropriate resistors, it can function effectively as both a voltmeter and an ammeter, making it a versatile tool in electrical measurements.
### Galvanometer as a Voltmeter
1. **Basic Principle**: A galvanometer can be converted into a voltmeter by using it to measure the potential difference (voltage) across a component in a circuit.
2. **Modification**: To use a galvanometer as a voltmeter, a high-resistance resistor, called a **shunt resistor**, is connected in series with the galvanometer. This arrangement ensures that most of the voltage is dropped across the shunt resistor, allowing only a small portion to pass through the galvanometer.
3. **Calibration**: The voltmeter is calibrated by applying known voltage levels and recording the galvanometer’s deflection. This allows the scale on the voltmeter to be marked with appropriate voltage values corresponding to the galvanometer’s deflection.
4. **Operation**: When a voltage is applied, the current that flows through the circuit causes the galvanometer needle to move. The degree of movement indicates the voltage, with a scale providing a direct reading.
5. **Sensitivity**: The high resistance of the series resistor allows the voltmeter to measure high voltages without drawing significant current, which could affect the circuit being measured.
### Galvanometer as an Ammeter
1. **Basic Principle**: A galvanometer can also be used to measure current by allowing the current to pass through the instrument directly.
2. **Modification**: To convert a galvanometer into an ammeter, a low-resistance resistor, known as a **shunt resistor**, is placed in parallel with the galvanometer. This configuration allows most of the current to bypass the galvanometer while a small fraction flows through it.
3. **Calibration**: The ammeter is calibrated similarly by passing known currents through the circuit and recording the corresponding deflections of the galvanometer. The scale is then marked with the current values.
4. **Operation**: When current flows through the circuit, the small portion that passes through the galvanometer causes the needle to deflect. The deflection indicates the current in the circuit, with the scale providing a direct reading.
5. **Range Extension**: By changing the value of the shunt resistor, the ammeter can be adapted to measure different ranges of current, from small to large values, without damaging the galvanometer.
### Summary
- **Voltmeter**: Measures voltage by using a high-resistance series resistor to protect the galvanometer. It shows the potential difference across a component.
- **Ammeter**: Measures current by using a low-resistance parallel shunt resistor, allowing most current to bypass the galvanometer. It shows the current flowing through the circuit.
By modifying a galvanometer with appropriate resistors, it can function effectively as both a voltmeter and an ammeter, making it a versatile tool in electrical measurements.