Why Did Our Geophysical Group Use a L&N Bridge Instead of a Slide-Wire Bridge?

AI Thread Summary
A geophysical group in Yuma, Arizona, utilized a Leeds and Northrup (L&N) bridge instead of a slide-wire bridge for measuring soil resistance in their search for water. The L&N bridge offers greater accuracy, which is crucial in geophysical measurements. Additionally, its portability is advantageous for fieldwork in challenging environments. The potential for thermal expansion and contraction in the slide-wire bridge could lead to inaccuracies in data due to high summer temperatures. Overall, the choice of the L&N bridge was driven by the need for precision and reliability in the hot climate.
hamburgler
Messages
22
Reaction score
0
My teacher gave us this problem to work on:

Homework Statement


Some years ago I worked with a geophysical group that was looking for water in the Yuma Arizona area. Boy what it hot! Because of the high temperatures in the summer, water was badly needed in large amounts to irrigate crops. Our crew inserted probes in the soil over large areas so we could measure the resistance of the soil and hopefully find water. The instrument that we used in this research was a Leeds and Northrup unit just like the one you used in your experiment. We did not use a slide-wire bridge. Give three reasons why a professional crew like I have described used a L&N bridge rather than the slide-wire bridge.

2. The attempt at a solution

1. A L&D bridge is far more accurate than a slide-wire bridge is in this situation.
2. It is more portable.
3. The heat may cause the wire in the slide-wire bridge to shrink/expand and cause discrepancies in the data.


The last two are just shots in the dark because I can't think of anything else beyond accuracy.
 
Physics news on Phys.org
No one?
 
Please? lol
 
I think 1) is because of 3) which is the correct answer. I am not very sure what an L&D bridge is though. I assumed they consisted of the arrangement of resistor boxes usually seen in labs.
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...

Similar threads

Replies
10
Views
5K
Replies
46
Views
8K
Replies
14
Views
7K
Replies
1
Views
10K
Replies
10
Views
10K
Replies
4
Views
8K
Replies
8
Views
5K
Back
Top