TECHNOLOGY AND

LIVELIHOOD EDUCATION

FOR GRADE 8

PERFORMING MENSURATIO

N AND CALCULATIO

N

Electrical Measurements Electrical measurements are the methods, devices and calculations used to measure electrical quantities. Measurement of electrical quantities may be done to measure electrical parameters of a system. Using transducers, physical properties such as temperature, pressure, flow, force, and many others can be converted into electrical signals, which can then be conveniently measured and recorded.

 

High-precision laboratory measurements of electrical quantities are used in experiments to determine fundamental physical properties such as the charge of the electron or the speed of light, and in the definition of the units for electrical measurements, with precision in some cases on the order of a few parts per million. Less precise measurements are required every day in industrial practice. Electrical measurements are a branch of the science of metrology.

Measurable independent and semi-independent electrical quantities comprise:- Voltage- Electric Current- Electrical Resistance and electrical conductance- Electrical reactance and susceptance- Magnetic Flux- Electrical charge by means of electrometer- Magnetic field by means of Hall sensor- Electric field- Electrical power by the means of electricity meter- S-Matrix by the means of network analyzer (electrical)- Electrical power spectrum by the means of spectrum analyzer

Measurable dependent electrical quantities comprise:- Inductance- Capacitance- Electrical impedance defined as vector sum of electrical resistance and electrical reactance- Phase between current and voltage and related quality factor- Electrical spectral density - Electrical phase noise- Electrical amplitude noise- Transconductance- Transimpedance- Electrical power gain- Voltage gain- Current gain- Frequency

Measuring Tool/Instrument:1. Test Light- A test light, test lamp, voltage tester, or mains tester is a very simple piece of electronic test equipment used to determine the presence or absence of an electric voltage in a piece of equipment under test.

2. Micrometer- A micrometer sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for precise measurement of components in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers.

3. Wire Gauge - Wire gauge is a measurement of how large a wire is, either in diameter or cross sectional area. This determines the amount of electric current a wire can safely carry, as well as its electrical resistance and weight per unit of lenght. Wire gauge is applicable to both electrical and non-electrical wires, being important to electrical wiring and to structural cable.

4. Ruler - A ruler, sometimes called a rule or line gauge, is an instrument used in geometry technical drawing, printing as well as engineering and building to measure distances or to rule straight lines. The ruler is a straightedge which may also contain calibrated lines to measure distances.

6. Ammeter – is an instrument used to measure the magnitude of an electric current of several amperes or more. An ammeter is usually combined with a voltmeter and an ohmmeter in a multipurpose instrument.

7. Voltmeter - instrument used to measure differences of electric potential, commonly called voltage, in volts or units that are multiples or fractions of volts.

8. Current Clamp - In electrical and electronic engineering, a current clamp or current probe is an electrical device having two jaws which open to allow clamping around an electrical conductor. This allows properties of the electric current in the conductor to be measured, without having to make physical contact with it, or to disconnect it for insertion through the probe.

9. Multitester - A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter would include basic features such as the ability to measure voltage, current, and resistance. 

 

System of Measurement A system of measurement is a set of units of measurement, which can be used to specify anything which can be measured and were historically important, regulated and defined because of trade and internal commerce. In modern systems of measurement, some quantities are designated as fundamental units, meaning all other needed units can be derived from them, whereas in the early and most historic eras, the units were given by fiat (see statutory law) by the ruling entities and were not necessarily well inter-related or self-consistent.

Common Units of Measurement:1. English System - An English system is defined as a system of measures or weights based or concerned with the foot, pound, second and pint. It is also described as a standard of measurements concerned with the pound, Fahrenheit degrees and inch. 2.Metric System - The metric system is a system of measuring. It has three main units:

* English Units and Equivalents * Metric Units and Equivalents * English To Metric equivalent * The Centimeter Graduation * The Inch Graduation

 

 

m The meter for length.

kg The kilogram for mass.

s The second for time.

The Multitester A multimeter can be a hand-held device useful for basic fault finding and field service work, or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.

•Parts Of a Multitester

•How To Use A Multitester: