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OHM'S LAW

 NejithK.Cifuentes45151015, MarcoH.Castellanos-45151000,CristianH.Cristancho,

45151043

ABSTRACT

In the lab it is to experimentally identify

all concepts related to Ohm's law and

their respective applications. 

I. INTRODUCTION

This lab aims to study Ohm's law, thislaw relates us the concepts of voltage

and current resistance, this says that

the relationship between current and

voltage will always be linear (in ideal

situations) and that this graph

expresses us a new feature, the

resistance which is the slope of the

voltage-current straight, for this they

will be making a series of assemblies

in which they will go to a series ofresistors, said resistors have nominal

output of 250mW, 500mW and 1W,

with this test seeks rated power of

these in addition to its temperature and

whith stand power, with the data

obtained are to generate graphics with

which we conclude about their

behavior at different currents and

voltages.

QUESTIONARY

1.Which physical phenomena

define the limit of the linearity of

a resistance?

Ohm's law determines that for some

materials such as metallic conductors

most current density and the electric

field are related through a constant

called conductivity characteristic of

each substance.

Ohmic resistivity of each material

depends on the material properties

and temperature and on the other

hand, the resistance of a substancedepends on the material shape and

resistivity . In general , the functional

relationship between temperature and

resistivity of a metal .

(panamahitek.com, 2016)

2.How varies the rated power of aresistor according to thetemperature variation? 

 As power is P =I^2 R then is directly

proportional to the resistance ofconductor or semiconductor materialand this varies Since this temperatureis inversely proportional to theresistance of the material , resistivity ofa metallic material increases withincreasing temperature , this isbecause ions driver vibrate withgreater amplitude , which makes itmore likely that a moving electroncollision with an ion, this prevents the

entrainment of electrons by the driverand therefore also the current. Theresistivity of non-metals decreaseswith increasing temperature, since athigher temperatures, more electronsare torn from atoms and gain mobility.

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3. What is the meaning of the

temperature coefficient?

Temperature coefficient, is an

intensive property of materials that

quantifies the relationship between the

change of physical property of a

material and the change in

temperature. Therefore, it is the

relative change of a physical property

when the temperature is changed, 1K,

the coefficient determines the increase

or decrease of electric resistance

according to variation of temperature

and the nature of each material. This

coefficient is called the letter α and in

formula is the resistance depending ontemperature change.

Table of coefficients of variation of

resistance per degree of

temperature 

4. What is the difference between

rated power and withstand power?

The rated power refers to the amount

of power that can flow through a

resistor so that this function optimally,at 100%, this is ideal for operation in

the same state, while the withstand

power refers the limit of power that can

withstand resistance to overcome this

limit resistance into an overstrain

which leads to the destruction of the

strength due to excess electricity.

REQUIREMENTS OF THE LAB PLAN

1. One resitencia trade value of 82 omhs

was chosen. 

Theoretical solution

The solution of theoretical of the circuitis: For the ohm’s law V=I*R we obtain

the following theoretical values of

voltage, current and resistance.

Simulation to 5v of the theoretical circuit

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Practical circuits In the next table show how

the current, power and the temperature

changes with the voltage obtaining different

results from those shown in the theoretical

values. The temperature exiting the

following equation:

assuming that the ambient temperature is

20°C.

Practical circuit with internal resistance of amperimeter

Practical circuit with internal resistance of voltmeter

Curve of v –

i (voltage-current)

Curve of R –T (resistancetemperature)

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Curve of P –i (power-current).

Simulation of practical circuit with voltmeter

Simulation of practical circuit with ammeter

Bibliografía panamahitek.com. (27 de 02 de 2016).

Obtenido de

https://es.wikipedia.org/wiki/Ley_de

 _Ohm#Definici.C3.B3n_de_resistivid

ad_y_su_relaci.C3.B3n_con_la_resist

encia