How Do You Calculate R1 and R2 for Temperature-Independent Resistance?

In summary, resistance is the measure of how much a material opposes the flow of electric current and is measured in ohms (Ω). Factors that affect resistance include the type of material, its length, cross-sectional area, and temperature. Resistance is different from resistivity, which is a measure of the material's inherent ability to resist current and only depends on the material. Resistance and resistivity are related through the formula R = ρ * L/A, and both are affected by temperature, with resistance generally increasing and resistivity decreasing (except for semiconductors) as temperature increases.
  • #1
frozen7
163
0
A resistor is to have a constant resistance of 30(ohm), independent of temperature. For this, an aluminium resistor with resistance R1 at 0(celcius) is used in series with a carbon resistor with resistance R2 at 0(celcius). Evaluate R1 and R2, given that [tex]\alpha 1[/tex] is 3.9 x 10^-3 for aluminium and [tex]\alpha 2[/tex] is -0.5 x 10^-3 for carbon.

Can anyone give me some clues to solve this question? Thanks in advance.
 
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  • #2
Start with the definition of alpha.
 
  • #3
Resistances in series ...
there's a way to represent these with a single equivalent resistance ...
 

Related to How Do You Calculate R1 and R2 for Temperature-Independent Resistance?

1. What is resistance and how is it measured?

Resistance is the measure of how much a material opposes the flow of electric current. It is measured in ohms (Ω) using a multimeter or other electrical measuring device. The higher the resistance, the more difficult it is for current to flow through the material.

2. What factors affect resistance?

There are several factors that affect resistance, including the type of material, its length, its cross-sectional area, and its temperature. Materials with higher resistivity (such as insulators) will have higher resistance. Longer materials and those with smaller cross-sectional areas will also have higher resistance. As temperature increases, so does resistance.

3. What is the difference between resistance and resistivity?

Resistance is a measure of how much a material impedes the flow of electric current, while resistivity is a measure of the material's inherent ability to resist the flow of current. Resistance depends on both the material and its dimensions, while resistivity only depends on the material.

4. How are resistance and resistivity related?

The relationship between resistance (R), resistivity (ρ), length (L), and cross-sectional area (A) is given by the formula R = ρ * L/A. This means that as resistivity increases, resistance also increases, and as length increases or cross-sectional area decreases, resistance also increases.

5. How does temperature affect resistance and resistivity?

Temperature has a significant impact on both resistance and resistivity. As temperature increases, the resistance of most materials also increases due to an increase in vibrations of the atoms within the material, impeding the flow of current. In contrast, resistivity generally decreases with increasing temperature for most materials, with the exception of semiconductors.

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