R= R0 * [1 + rho( t2-t1 ) ]
so from this equation ,
rho= R-R0/[R0(t2-t1)]
where
rho- coefficient of resisivity
R-resistance at any time t
R0- resistance at 00C
t2-final temperature
t1-initial temperature
positive temperature coefficient vs. negative temperature coefficient resistance increases or decreases with increase of temperature, respectively.
That will depend on the temperature coefficient of resistance of the device, which could be positive (i.e. resistance increases with increasing temperature), negative (i.e. resistance decreases with increasing temperature), or zero (i.e. resistance is unaffected by temperature changes).
A NTC thermistor is a temperature sensor that has a "negative temperature coefficient". That means as temperature goes up, the resistance of the device goes down over it's operating range.
A thermistor changes it's resistance depending on temperature. Hence Thermal-Resistor. (Thermistor) It is all to do with the crystal structure of the substance the thermistor is made of. Some increase their resistance as temperature rises, called Positive Thermal coefficient, 'PTC'. Others reduce their resistance with increasing temperature, called Negative Thermal Coefficient. 'NTC'. They can be used in a feedback loop of a simple amplifier and switch circuits, to control temperature of a device. They can be calibrated for use in a current loop, to directly measure temperature, like a thermometer. They can be used to stop surges in start up circuits, initially giving a high resistance until things warm up. Or used to apply a large current and then reduce as things warm up. (Like in the old degaussing coils on a colour CRT).
Electrical resistance depends on the temperature but not the biased voltage.AnswerIt's resistivity that can be affected by temperature, which means that resistance is indirectly affected by temperature.
The temperature coefficient of resistance is a number used to predict how the resistance of a material changes with changes in temperature. Typically the units are either resistance per temperature or 1/temperature depending on which equation is used for the calculations. For example, in copper the temperature coefficient of resistance is about 0.0039 per change in degrees Celsius. A positive temperature coefficient of resistance means that the resistance of the material will increase as temperature increases. As per the equation or say unit of resistance temperature coefficient, its definition can be given as below: " Rise in temperature per unit initial resistance, when temperature is raised by one degree Celsius is called the resistance temperature coefficient."
• ntc 'negative temperature coefficient': its resistance decreases as the temperature increases• ptc 'positive temperature coefficient': its resistance increases as the temperature increases
Negative temperature coefficient of resistance means that as the temperature of a piece of wire or a strip of semiconducting material increases, the electrical resistance of that material decreases.
most metals resistance increases with temperature
The unit of temperature coefficient of resistance is ohm per ohm per degree Celsius or say resistance per resistance per degree Celsius.
to investigate change in resistance as temperature is varied
This depends on the type of conductor. If the conductor has a positive coefficient the resistance will increase. If the conductor has a negative temperature coefficient the resistance will decrease.
The metal with the lowest temperature coefficient is Platinum. Its temperature coefficient of resistance is among the lowest of all metals, making it a preferred choice for applications where stability in resistance over a wide temperature range is required.
Well, there's typically two types of materials-Those with positive temperature coefficient and those with negative temperature coefficient. Positive temperature coefficient are those whose resistance increases as temperature increases. Negative temperature cofficient are those whose resistance decrease when the temperature increase. There are however some alloys such as Manganin& Constantan whose resistance is not affected by temperature
"Temperature coefficient" means, how does a certain physical quantity vary, depending on the temperature. In this case, the physical quantity in question is probably the electrical resistance, or the electrical resistivity.
Some materials have negative temperature coefficients of resistance, and some have positive temperature coefficients. Carbon is an example of a substance with a negative thermal coefficient of resistance, so it's resistance will decrease as it gets hotter.
What happens depends on the temperature coefficient of the diode. If that diode has a positive temperature coefficient, it resistance increases with increased temperature. A diode with a negative temperature coefficient does the opposite.