Parallel-plate air capacitor

[vegamontalvo]

Each plate of a parallel-plate air capacitor has an area of 0.0070 m2, and the separation of the plates
is 0.030 mm. An electric field of 4.0 × 106 V/m is present between the plates. The capacitance of the
capacitor, in pF, is closest to:?


The capacitive network shown is assembled with initially uncharged capacitors. A potential difference, Vab = +100 V, is
applied across the network. The switch S in the network is kept open throughout.

 

[Klockan3]

Capacitance is electric energy per charge, you should be able to calculate the electric energy for a given charge setup so just put Q -Q on the capacitor and continue on from there.

As for the second it is just about knowing how to calculate parallel and series of capacitors. You should be able to prove these from the definition of capacitance.

If you have any problems try to start, post how far you got and I can give you more from there.

 

[vegamontalvo]

yes i need help to start! thank you

 

[tiny-tim]

welcome to pf!

hi vegamontalvo! welcome to pf!

(try using the X² icon just above the Reply box )

Each plate of a parallel-plate air capacitor has an area of 0.0070 m2, and the separation of the plates
is 0.030 mm. An electric field of 4.0 × 106 V/m is present between the plates. The capacitance of the
capacitor, in pF, is closest to:?

what formulas do you know relating E d A Q and C for a capacitor ?

Capacitance is electric energy per charge …

no, capacitance = charge per voltage

 

[rwisz]

I would like to clarify that the capacitance of the parallel-plate air capacitor can be calculated using the formula C = ε₀A/d, where ε₀ is the permittivity of free space, A is the area of the plates, and d is the distance between the plates. Using the given values, the capacitance of the capacitor is approximately 7.78 pF.

Regarding the second part of the content, I would like to point out that the potential difference, Vab = +100 V, applied across the network will not affect the capacitance of the parallel-plate air capacitor. The capacitance is a physical property of the capacitor and is not affected by external factors such as potential difference.

Furthermore, the switch S being kept open throughout means that no current is flowing through the circuit, and therefore, the capacitor remains uncharged. The potential difference across the network will only be present when the switch is closed and current flows through the circuit.

In conclusion, the capacitance of the parallel-plate air capacitor is approximately 7.78 pF and the potential difference of +100 V across the network will not affect its capacitance as long as the switch remains open.