Moving Coil Galvanometer Ammeter And Voltmeter Potential Energy Of A Dipole
Moving Coil Galvanometer
Basic principle and construction:
- A moving coil galvanometer consists of a coil of wire suspended between the poles of a permanent magnet.
- When a current flows through the coil, it creates a magnetic field that interacts with the magnetic field of the permanent magnet, causing the coil to rotate.
Controlling torque:
- The controlling torque in a moving coil galvanometer is provided by a spring attached to the coil. The spring opposes the rotation of the coil, providing a restoring force.
Current sensitivity and voltage sensitivity:
- The current sensitivity of a moving coil galvanometer is defined as the deflection produced by a current of one ampere. The voltage sensitivity is the deflection produced by a voltage of one volt.
Conversion to ammeter and voltmeter:
- A moving coil galvanometer can be converted into an ammeter by connecting a shunt resistor in parallel with the coil.
- To convert it into a voltmeter, a series resistor is connected in series with the coil.
Shunts and multipliers:
- Shunts and multipliers are used to extend the range of a moving coil galvanometer. A shunt is a low-resistance resistor connected in parallel with the coil, while a multiplier is a high-resistance resistor connected in series with the coil.
Potential Energy of a Dipole
Expression for potential energy:
- The potential energy of a dipole in an electric field can be expressed as: $$U = - \vec{p} \cdot \vec{E}$$
where is the dipole moment, is the electric field, and is the angle between the dipole moment and the electric field.
Dipole in a uniform electric field:
- In a uniform electric field, the potential energy of a dipole is given by: $$U = - pE \cos\theta$$
Torque on a dipole in a uniform electric field:
- The torque acting on a dipole in a uniform electric field is given by: $$\vec{\tau} = \vec{p} \times \vec{E}$$
Potential energy of a dipole in a non-uniform electric field:
- The potential energy of a dipole in a non-uniform electric field can be expressed as: $$U = -\int\vec{p}\cdot d\vec{E}$$
Additional Concepts
Ballistic galvanometer:
A ballistic galvanometer is a moving coil galvanometer that is used to measure the total charge passed through it.
Sensitivity of a galvanometer:
The sensitivity of a galvanometer is defined as the deflection produced by a specific current or voltage.
Resolution of a galvanometer:
The resolution of a galvanometer is defined as the smallest change in current or voltage that can be detected by the galvanometer.
Potentiometer:
A potentiometer is a device that can be used to measure an unknown voltage by comparing it to a known voltage.
Voltmeter with infinite resistance:
A voltmeter with infinite resistance is a voltmeter that does not draw any current from the circuit being measured.
BETA
