State and describe briefly at least one measuring instrument for each of the following physical quantities:
a) Mass
b) Illumination
c) Density
d) Irradiance
e) Temperature
f) Pressure
g) Flowrate
Answer (2)
Measuring instruments are crucial in physics for quantifying various physical quantities. Each instrument works on specific principles to ensure accurate measurements of mass, illumination, density, irradiance, temperature, pressure, and flow rate. For example, a balance scale measures mass by comparing it to known masses, while a lux meter measures illumination by detecting light intensity.
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To measure various physical quantities, specific instruments are used. Here is a brief description of instruments for each of the mentioned quantities:
a) Mass : A balance scale is commonly used to measure mass. It consists of a horizontal beam with two pans at each end. When an object is placed on one pan and known masses on the other, the beam balances when the masses are equal, thus allowing the measurement of mass.
b) Illumination : A lux meter is used to measure illumination. It works by capturing light through a photodetector, which converts the light's intensity to an electrical signal that is displayed in lux, the unit of illumination.
c) Density : A hydrometer is an instrument used to measure the density of liquids. It is a sealed glass tube that floats in the liquid. The level to which it sinks indicates the liquid's density, usually marked on the side of the hydrometer.
d) Irradiance : A pyranometer measures solar irradiance. It measures the solar power's intensity per unit area on the Earth's surface, typically in watts per square meter, by capturing sunlight using a sensor.
e) Temperature : A thermometer is widely used to measure temperature. It can contain a liquid like mercury or alcohol that expands or contracts with temperature changes, allowing for the reading of temperature on a calibrated scale.
f) Pressure : A barometer is an instrument used to measure atmospheric pressure. It can be either a mercury barometer or an aneroid barometer, both of which provide pressure readings that help in weather predictions and altitude measurements.
g) Flowrate : A flowmeter, or flow sensor, measures the rate of flow of a fluid. Various types exist, such as volumetric or mass flow meters, which use different principles like differential pressure, positive displacement, or turbine mechanisms to calculate flow rate.
