View Single Post
  #14   Report Post  
Posted to uk.d-i-y
harry harry is offline
external usenet poster
 
Posts: 9,188
Default Another physics question

On Jan 6, 9:46*pm, geoff wrote:
In message
,
harry writes





On Jan 6, 5:25*pm, The Natural Philosopher
wrote:
Neil wrote:
If you have a container and you put two vertical parallel wires in it,
why can't you determine the quantiy of a liquid poured into that
container based on the resistance measured between the two wires?


you can.


If the material is conductive.


You can also measure the capacitance if its an insulator


But modern oil gauges and height gauges prefer to use ultrasonic
rangefinding on the top of the liquid.


Not always a good idea to have electrical conductors in flammable liquids..


The traditional automotive petrol guage sender is immersed in petrol/
petrol vapour. No danger if there is no air.


Much traditional instrumentation in boilerhouses depends on electrodes
immersed in water or sometimes mercury eg for determining *draught in
chimneys and CO2 levels in combustion gases via the resistance of the
water.


Fluids don't have capacitance.


Duh - The wires have a capacitance between them and the fluid (assuming
its an insulator) acts as a dielectric between the wires

--
geoff- Hide quoted text -

- Show quoted text -


I thought the OP was about measuring liquid?
Which is not a capacitor.