# Temperature dependence of resistors help please

• clickcaptain
In summary, the conversation is discussing the final temperature of a toaster with a Nichrome heating element based on its resistance and initial and final current values. The equation for temperature coefficient of resistivity is mentioned but it is unclear how to use it. The expert suggests finding the temperature dependence of the resistivity of nichrome and using this along with the resistance change to determine the final temperature.
clickcaptain

## Homework Statement

A toaster with a Nichrome heating element has a resistance of 150 omega at 20degrees Celsius and an initial current of 2 A. When the heating element reaches its final temperature, the current is 1.73 A. What is the final temperature of the heating element?

## Homework Equations

Not sure if they will help but...

(for the equations below i will use p as rho)

R = (p) (L/A)

temperature coefficient of resistivity, alpha = ((p - p0)/p0)/ (T - T0)

## The Attempt at a Solution

The only equation relating to the temperature of resistors was the temperature coefficient but I'm not sure how to use it. Thanks for the help!

You need the temperature dependence of the resistivity of nichrome.
Assuming the voltage is the same then from the current you can work out the resistance change and from the temperature coefficent - the temperature change,

mgb_phys said:
You need the temperature dependence of the resistivity of nichrome.

I'm not sure what you mean here, could you expand a little please? Thanks.

The resistivity of nichrome (like any other metal) depends on it's temperature
You can look up the value in a data book or on the web.
Then you can use this and the resistance change to find the temperature.

## 1. What is the temperature dependence of resistors?

The temperature dependence of resistors refers to the change in resistance of a material as the temperature changes. This change can be either positive, where the resistance increases with temperature, or negative, where the resistance decreases with temperature.

## 2. Why does temperature affect the resistance of a material?

Temperature affects the resistance of a material because it changes the behavior of the electrons within the material. As the temperature increases, the atoms in the material vibrate more, which causes more collisions between the electrons and the atoms. This increases the resistance of the material.

## 3. How does the temperature coefficient of resistance play a role in temperature dependence?

The temperature coefficient of resistance (TCR) is a measure of how much the resistance of a material changes with temperature. It is a constant value that varies for different materials. The TCR is used to predict the change in resistance of a material as the temperature changes.

## 4. What is the difference between positive and negative temperature dependence of resistors?

Positive temperature dependence means that the resistance of a material increases as the temperature increases. This is typically seen in metals and semiconductors. Negative temperature dependence means that the resistance decreases as the temperature increases. This is seen in materials like carbon or thermistors.

## 5. How can the temperature dependence of resistors be compensated for in electronic circuits?

The temperature dependence of resistors can be compensated for by using materials with a low TCR, such as certain types of metal alloys. Temperature compensation circuits can also be used, which involve adding a second resistor with a different TCR to cancel out the temperature dependence of the first resistor.

• Introductory Physics Homework Help
Replies
1
Views
814
• Introductory Physics Homework Help
Replies
4
Views
4K
• Introductory Physics Homework Help
Replies
2
Views
1K
• Introductory Physics Homework Help
Replies
41
Views
4K
• Introductory Physics Homework Help
Replies
6
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
709
• Introductory Physics Homework Help
Replies
5
Views
3K
• Introductory Physics Homework Help
Replies
3
Views
908
• Introductory Physics Homework Help
Replies
3
Views
908
• Introductory Physics Homework Help
Replies
19
Views
2K