What Caused the Lower Resistance in the Second Graph?

  • Context: Undergrad 
  • Thread starter Thread starter MementoMori96
  • Start date Start date
  • Tags Tags
    Hall effect Voltmeter
Click For Summary
SUMMARY

The discussion centers on the observed lower resistance in a p-doped germanium (Ge) sample when subjected to a magnetic field, specifically at B = 0. The participant hypothesizes that the accumulation of positive charges leads to a lower voltage and resistance. Concerns are raised regarding the large error bars in the measurements and the impact of temperature on resistance readings. The participant confirms that temperature was controlled, but the error bars are attributed to instrument limitations.

PREREQUISITES
  • Understanding of p-doping in semiconductor materials
  • Familiarity with resistance measurement techniques in laboratory settings
  • Knowledge of magnetic field effects on electrical properties
  • Basic statistical analysis, including Z tests
NEXT STEPS
  • Research the effects of magnetic fields on semiconductor resistance
  • Explore advanced error analysis techniques for laboratory measurements
  • Study the principles of charge accumulation in semiconductor physics
  • Investigate temperature control methods in electrical resistance experiments
USEFUL FOR

Researchers in semiconductor physics, laboratory technicians conducting resistance measurements, and students studying the effects of magnetic fields on electrical properties of materials.

MementoMori96
Messages
13
Reaction score
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?
 

Attachments

  • resistenza.jpg
    resistenza.jpg
    19.8 KB · Views: 533
  • R(B).jpg
    R(B).jpg
    28 KB · Views: 562
  • Immagine.png
    Immagine.png
    4.9 KB · Views: 574
Physics news on Phys.org
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?
 
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?
 

Similar threads

Undergrad Resistance and magnetic field effects for p-doped Ge
  • · Replies 9 ·
Replies
9
Views
2K
Undergrad How to understand experiment to measure heat capacity of solid?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate 4 probe conductivity in discs (Smits)
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Resistance of Platinum decreases with an increase in temperature ?
  • · Replies 2 ·
Replies
2
Views
7K
Lab: Plot graph of resistance, R (in Ohms) versus 1/d^2
  • · Replies 21 ·
Replies
21
Views
11K
Graduate Why do conductivities and resistivities change with magnetic field strength?
  • · Replies 2 ·
Replies
2
Views
1K
Engineering Voltmeter and ammeter calculation in a circuit
  • · Replies 6 ·
Replies
6
Views
5K
Why Don't Voltmeter Readings Across Different Resistors Add to Source Voltage?
  • · Replies 26 ·
Replies
26
Views
5K
Calculating the Hall Coefficient for a sample of germanium
  • · Replies 2 ·
Replies
2
Views
4K
How Can a DC Milliammeter Be Adapted to Measure 150V Accurately?
  • · Replies 11 ·
Replies
11
Views
3K