Measuring Range Extension "homework"

In summary: And you know that the series resistance is 247.3 k##\Omega## because you were told so.So you just see what the meter reads when this series resistance is 247.3 k##\Omega##. And then you can calculate what would be the reading when the series resistance is increased by 20% to 296.76 k##\Omega##.And that is exactly what you have done in your last line. Only you have added an extra 324 mV for the meter.That is right, the voltage drop over the meter is 270 mV. But the meter reading is not 270 mV
  • #1
Apo_GER
2
0
Moved from a technical forum, so homework template missing
a)
dimension the moving-coil movement so that it indicates full deflection at 25 V
given Values:

Voltage Source: U2Max = 25V;
moving-coil movement: IM = 100µA; UM = 270mV

Rv = ( U2Max - UM ) / IM = (25V - 270mV) / 100 µA = 247,3kΩ

b) the internal resistance is increased by 20 % due to tolerances in production. What does the moving coil movement indicate at an output voltage of 25V

My approach is the following...

RM = UM / IM = 270mV / 100µA = 2700Ω

now: it is 20% higher --> RM.Tol = RM *1,2 = 3240Ω

...
...

The Answer is : The moving coil movement indicates 24.945 V
 
Physics news on Phys.org
  • #2
Hallo Apo, :welcome:

Nor clear what your dots are representing...
You found a new value for RM and the question is: how far does the meter that you built with this coil and the 247.3 k##\Omega## series resistance go on the scale, when the actually applied voltage is 25 V ?

(and you already know that 100 ##\mu##A gives full scale)
 
  • #3
Hi BvU
The dots are representing the missing "method" to get to the answer.

In task-part a) i came to the result, that i have to add an other resistance Rv with 247,3kOhm in series so that the moving coil movement shows full deflection.

In b) the internal resistance increases by 20% and voltage source supplies 25 V.
The question is what does the moving coil movement shows?
The answer has to be 24.945 V.

My Idea:

The inner resistance increase by 20%...
--> Rm = Um/Im --> 270mV * 100µA = 2700Ohm
--> RM.Tol = Rm * 1,2 = 3240OhmNow the current strength changes? or the voltage drop? "Over moving coil movement"

--> UM.Tol = RM.Tol * IM = 3240Ohm * 100µA = 324mV

--> Rv = ( U2Max.Tol - UM.Tol ) / IM = > 247,3kOhm = ( U2Max.Tol - 324mV ) / 100µA => (247,3kOhm * 100µA ) + 324mV = U2Max.Tol
=> U2Max.Tol = 25,054 (not true)
 
  • #4
Hehe, with the answer given you should be able to draw your own conclusion ...:rolleyes:

The intention of he exercise is
for an applied voltge of 25 V the current is now a bit lower. The ideal coil showed full scale at 100 ##\mu##A, but the coil with 20% more resistance will cause a smaller current, so it does not go all the way to full scale. With full scale (= 100 ##\mu##A ) marked as 25V for the ideal coil, the non-ideal coil shows ...

extra exercise: how big is now the voltage drop over the coil ?
 

1. What is "Measuring Range Extension" homework?

"Measuring Range Extension" homework is a type of assignment that typically involves using experimentation and scientific tools to expand the measurement capabilities of a given device or instrument. This can include techniques such as calibration, interpolation, extrapolation, and error analysis.

2. Why is "Measuring Range Extension" important in scientific research?

"Measuring Range Extension" is important in scientific research because it allows scientists to accurately measure and analyze a wider range of data. This can lead to more precise and reliable results, which are essential for drawing accurate conclusions and making informed decisions in the scientific community.

3. What are some common techniques used for "Measuring Range Extension" homework?

Some common techniques used for "Measuring Range Extension" homework include calibration, which involves adjusting a measuring device to accurately reflect known values; interpolation, which involves estimating values within a given range based on known data points; and extrapolation, which involves extending known data points beyond their given range.

4. How does "Measuring Range Extension" relate to experimental design?

"Measuring Range Extension" is an important aspect of experimental design because it allows scientists to ensure that their data is accurate and reliable. By expanding the range of measurement capabilities, scientists can gather more data and make more precise observations, leading to stronger experimental designs and more robust conclusions.

5. Can "Measuring Range Extension" be applied to any type of measurement?

Yes, "Measuring Range Extension" can be applied to any type of measurement as long as there is a need to expand the range of data being collected. This can include measurements of length, mass, time, temperature, or any other physical quantity. The techniques used may vary depending on the specific type of measurement being extended.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
23
Views
9K
Back
Top