Measurement Devices in Physics
Among the most important measurement instruments used in physics are the following:
Ammeter
An ammeter is designed to measure electric currents within electrical circuits. It is characterized by its low resistance and is connected in series within the circuit to ensure a constant current flow. There are two primary types of ammeters: analog and digital.
Most standard ammeters consist of a thin wire coil wound around a soft iron core, which is suspended between the poles of a permanent magnet. When current flows through the coil, both the coil and the core rotate, aligning the magnetic field of the coil with that of the permanent magnet.
A pointer moves along a graduated scale to indicate the reading in amperes, allowing the ammeter to measure a wide range of currents, from microamperes to larger values.
Galvanometer
A galvanometer operates on a principle similar to that of an ammeter, specifically designed to measure weak currents. Its notable features include:
- Consistent scaling.
- Resistance to interference from stray magnetic fields.
- High precision, capable of manufacturing devices with accuracy up to 0.1%, suitable for measuring weak charges and currents.
- Low power consumption in the coils, typically ranging from 0.5 to 3 watts.
- Insensitivity to temperature variations.
- Versatility in function, as it can operate as an ammeter, voltmeter, or ohmmeter.
Voltmeter
A voltmeter is utilized for measuring the voltage difference across various components in an electrical circuit, such as resistors, capacitors, and batteries. It is connected in parallel within the circuit to ensure a constant voltage, and it features very high resistance.
Ohmmeter
An ohmmeter is a device specifically used to measure electric resistance. It provides direct resistance values through a moving dial, and it requires a connection to an internal voltage source to generate the necessary current for its operation. Various resistors are connected to facilitate accurate current flow and thus, the correct measurement of resistance.
Multimeter
A multimeter is a versatile instrument capable of measuring current, voltage, or electrical resistance via dedicated switches for each function. It is commonly used by electricians during their work.
Hydrometer
A hydrometer is composed of a long glass tube that is closed at both ends and is used for measuring the density of liquids.
Venturi Meter
This device measures the flow rate of liquids and their discharge rate in flow tubes, such as fuel and water pipes.
Viscometer
A viscometer is used to assess the viscosity of liquids. Viscosity refers to the resistance of a liquid or gas to flow, impacting processes like spraying or filling voids.
Micrometer
A micrometer provides precise measurements of length, thickness, and depth, achieving accuracy down to fractions of a millimeter. It is recognized for its reliable and comprehensive measurements, integrating both scale gauges and micrometer screw gauges into one device.
Vernier Caliper
This instrument measures the diameter or radius of a cylinder or sphere and is capable of measuring three types of dimensions:
- External dimensions, thickness, and diameter of an object.
- Internal dimensions of an object, or the inner diameter of pipes and tubes.
- Depth or height of an object resting on a surface, or the depth of a hole in an item.
Spring Scale
A spring scale measures an object’s mass or weight using a specific weight or mass scale. Some spring scales function without arms, such as hanging scales, and are capable of measuring forces applied through the scale in any direction.
Mass Measurement Devices
These devices vary in design and precision based on the amount of mass being measured, such as:
- The large scale, used for measuring very large masses like that of a vehicle.
- The double-pan balance, suitable for measuring masses up to several kilograms.
- The sensitive digital scale, designed for measuring masses that range from a few grams to several kilograms.
Time Measurement Devices
These devices differ in design and accuracy, including:
- Analog clocks, which indicate time in hours and minutes without sufficient precision for seconds and fractions of a second.
- High-precision digital clocks, capable of measuring time down to fractions of a second, widely used in scientific experiments and sporting events due to their high accuracy.
Spectrometer
A spectrometer is utilized for measuring the wavelength of light.