uplearn resistivity

When describing a thermistor, NTC stands for...

Negative temperature coefficient

Is a thermistor an insulator, semiconductor, or conductor??

Semiconductor

Select the correct graph for an NTC thermistor

When the temperature of an NTC thermistor increases what happens to free charge carriers and resistance...

The number density of free charge carriers increases and the resistance decreases

uses of thermistors:

The resistance of a thermistor changes in response to temperature.
∙   ∙ The uses of a thermistor are therefore those related to sensing temperature changes.
∙   ∙ Good examples include heat alarms and kettles

Select the correct I-V graph for an NTC thermistor

As the length of a section of wire increases, its resistance ...

Increases because the charge carriers have to travel through more resistive material

relationship between resistance and length of wire…

directly proportional

As the cross-sectional area of a piece of wire increases, its resistance…

Decreases

because the movement of the charge carriers becomes less impeded, which means that resistance decreases

The resistance of a section of wire relationship with its crossectional area…

inversely proportional

The resistivity of a component depends on...

what material it is made from

The units of resistivity are:

ohm metre

The definition of 1Ωm is...

A material has resistivity of 1Ω when a cubic metre of material has a resistance of 1Ω

Provided that the temperature is constant, resistivity...

is a constant for each material

Several measurements are taken during this experiment. Which of the following is the independent variable??

Length of wire

Which of the following plots should be used to represent that data graphically??

Length of wire on x-axis, resistance of the wire on the y-axis

Thermistor (Negative Temperature Coefficient or NTC Thermistor)

An electrical component that has a resistance that decreases as the temperature increases

Resistivity

A property of a material, measured in Ω m. ρ = RA/l where ρ = resistivity (in Ohm.metres (Ω⋅m)), R = resistance (in Ohms), A = area (in m2) and l = length of wire (in m).

A material has resistivity of 1 Ω m when a cubic metre of material has a resistance of 1 Ω

A wire has a resistivity of 0.005 Ωm. What would the resistivity be if the length of the wire was doubled and the diameter was halved

length and diameter don’t have any effect on resistivity

Which one of these factors would cause the resistivity of a wire to change??

Increasing the temperature