What Caused the Lower Resistance in the Second Graph?

In summary, the conversation discusses a laboratory experiment involving a sample of Ge with p-doping. The individual performed measurements of V vs I and V vs B, with a fixed current of 8 mA, and obtained two images. They also noticed that at B = 0, the resistance was lower than the resistance in the first graph, and speculated that this may be due to an accumulation of positive charges. The conversation also touches on the issue of error bars and temperature control in the experiment.
  • #1
MementoMori96
13
0
Hi, in laboratory i had a sample of Ge with p-doping. In a first place i have done different measure V vs I (first image)

Then i insert the sample in a magnetic field perpendicular to the sample.

And i have done measure of V vs B (with a fixed current at 8 mA) and i obtained the second image.

As you can see at B = 0 the R is lower than the resistance of the first graph. Why ?

I suppose this third image

The is an accumolation of positive charges at right and so we measure a lower Voltage with a lower resistance

Can be this correct?
 

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  • #2
MementoMori96 said:
As you can see at B = 0 the R is lower than the resistance of the first graph. Why ?
It looks like the top of your error bar at B=0 is close to what you measured in the first test. Why are the error bars so large?

Also, temperature will affect the "resistance" reading. How did you control for temperature?
 
  • #3
Yes is close but with a Z test alpha 5% the two values are not compatible. The error bars are large due to the instruments. The temperature is the same.

What do you think about my idea?
 

1. What is a voltmeter and how does it work?

A voltmeter is an instrument used to measure electrical potential difference, also known as voltage. It typically has two probes that are connected to the circuit being measured. The voltmeter measures the voltage by using a sensitive galvanometer, which is a device that detects small electrical currents, and then displays the measurement on a calibrated scale.

2. What is the Hall effect and how is it related to voltmeters?

The Hall effect is the production of a voltage difference across an electrical conductor when a magnetic field is applied perpendicular to the current flow. This phenomenon is used in voltmeters to measure the strength of a magnetic field by measuring the voltage perpendicular to the direction of the current flow. This is known as a Hall effect voltmeter.

3. What are the applications of a voltmeter and the Hall effect?

Voltmeters and the Hall effect have a wide range of applications in various fields such as electrical engineering, physics, and materials science. They are commonly used to measure voltage in circuits, magnetic field strength in materials, and to study the properties of semiconductors and other materials.

4. Can a voltmeter be used to measure AC and DC voltage?

Yes, some voltmeters are designed to measure both AC and DC voltage. However, there are also specialized voltmeters that are specifically designed for either AC or DC voltage measurements. It is important to select the correct type of voltmeter for the type of voltage being measured.

5. What are the limitations of using a voltmeter and the Hall effect for measurements?

One limitation is that the presence of a magnetic field can affect the accuracy of the measurements. Additionally, the sensitivity of the voltmeter and the Hall effect sensor can be affected by external factors such as temperature and humidity. It is important to calibrate the instrument regularly and minimize external influences for accurate measurements.

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