Ohmeter

Universidad de San Carlos
Technical English I
Facultad de Ingenieria
Oral Presentation Report
Section: G

“Measurement Instruments: Ohmmeter”

Luisa Fernanda Ramirez Cruz 2011-14745Carlos Gustavo Fuentes Mendoza 2011-14126

Introduction

Measurement instruments are the ones who we use to measure certain units and formal test methods. Some of them are used for different physicalquantities, as in this case electricity. The ohmmeter is a measurement instrument to measure electrical resistance, used by electricians, engineers, mechanics, etc.

Objectives
* To know what ameasurement instrument is.
* Develop oral skills, fluency, voice tone, etc.
* Research for an instrument specialized in any physical quantity and explain.

Ohmmeter

An ohmmeter is anelectrical instrument that measures electrical resistance. Electrical resistance is the opposition to an electric current, a flow of electric charge or rate of flow of an electric charge in this case.Electrical resistance is measured in ohms, that is where the name ohmmeter comes from.

It is designed using a small battery to apply voltage to a resistance. It also uses a galvanometer, aninstrument to measure and detect electric current, which was marked in ohms. So, the scale that the galvanometer uses works with the fixed voltage from the battery, then the resistance as the resistanceis decreased, the current through the scale will increase. Less resistance equals a bigger current.

Other kind of ohmmeters uses electronic circuits. One of them passes a constant current throughthe resistance. Meanwhile the other one measures the voltage across the resistance. Then we need to use the Ohm’s Law formula to find the value of resistance:
R=VI
R= resistance
V= voltage
I=current

R=VI
R= resistance
V= voltage
I= current

Commonly it is used by electric technicians to turn the power of in electrical devices, and discover a problem. In engineering it is used to...