What is a Conversion Privilege?
The conversion method refers to when the exploration of an object encounters obstacles, frustrations and obstacles in the process of creative invention, or when the solution to the problem is not ideal, then the angle of observing and thinking about the problem is changed, and the method of application or implementation is changed. A method of thinking that changes the way to solve a problem, or changes the internal structure of things, so that the problem is clarified and a satisfactory result is obtained. [1]
- In physical experiments, many physical quantities cannot be directly measured by instruments due to their attribute relationships, or are difficult to measure, or difficult to accurately measure. Therefore, these physical quantities are often converted to other physical quantities for measurement, and then the physical quantities to be measured are obtained in reverse. The method is called the conversion method. [2]
- First, the parameter conversion method
- The parametric conversion method uses a transformation relationship between various physical quantities to measure a certain physical quantity. This method runs through almost the entire field of physical experiments. For example, in the experiment of measuring the elastic modulus of metal by the tensile method, the elastic modulus E is to be measured, and the actual measurement is the stress.
- Second, the energy conversion method
- The energy conversion method uses a transducer (such as a sensor) to convert one form of energy into another form of energy, thereby obtaining another physical quantity by measuring another physical quantity. Due to the convenience of electrical quantity measurement, non-electric quantity is usually converted into electrical quantity measurement. Common energy conversions include thermoelectric conversion, piezoelectric conversion, photoelectric conversion, and magnetoelectric conversion.
- Thermoelectric conversion is the conversion of thermal quantities into electrical quantities. Common thermoelectric sensors include thermistors, PN junction sensors, and thermocouples. The use of temperature difference electromotive force to measure temperature is to convert the temperature difference into a potential difference through thermoelectric conversion. The potential difference gives the temperature to be measured.
- Piezoelectric conversion is a measurement that converts pressure into electrical quantities. Loudspeakers are common transducers. Piezoelectric conversion is often used for thickness and speed measurement. The experiment "measurement of sound velocity" is the application of piezoelectric conversion.
- Photoelectric conversion is the measurement of converting optical quantities into electrical quantities. The basic principle is the photoelectric effect. Common transducers include photocells, photomultiplier tubes, photovoltaic cells, and photosensitive tubes. The experiment "measures Planck constant using the photoelectric effect" And the experiment "Single slit diffraction light intensity distribution and measurement" is the application of photoelectric conversion.
- Magnetoelectric conversion is a measurement that converts magnetic quantities into electrical quantities. It mainly uses the Hall effect of semiconductor materials. The transducer is a Hall element. The experiment "Hall effect experiment" is the application of magnetoelectric conversion. [3]
- Measuring instruments: stopwatch, ammeter, voltmeter,
- Deformation or movement of objects can prove that some objects are subject to force; experiments in the Madenburg hemisphere can prove the existence of atmospheric pressure; the appearance of fog can prove that water vapor is contained in the air; the formation of shadows can prove that light travels in a straight line; Phenomena can prove that the moon is not a light source; Oersted experiments can prove that there is a magnetic field around the current; compass compass can prove the existence of the geomagnetic field; lead experiments can prove that there is gravity between molecules; moving objects can do work to prove that it has Yes; the magnetic strength of the electromagnet can be displayed by the amount of iron nails attracted by the electromagnet; all the sounding bodies are vibrating, etc., by popping up the table tennis caused by tapping the tuning fork.