The Maths and Science Thread - Collection of Problems and Facts

[Varun]

Can someone tell me in simple words - What is a capacitor? I can't seem to understand anything on wikipedia.

 

[blake]

Er...

It's a device used to store and release electricity, which consists basically of two conductive surfaces separated by a dielectric. They can be used to block the flow of a direct current while allowing an alternative current to pass..

and yeah.

 

[Varun]

Thanks much! Now I have a rough idea!

 

[Pranav]

It's something similar to a resistor (you must have studied about it). It doesn't allow the flow of DC (direct current, provided by a battery) to pass through it, and at the same time allows the flow of AC (alternating current). Whereas, a resistor allows the flow of both the currents. It's this unique property of a capacitor that is manipulated in various forms for commercial purposes.

Capacitance = Charge/Voltage

or C=Q/V

S.I Unit = farad.

(Just like the Ohm's law where we have R=V/I)

 

[Varun]

Thanks Mate! I was just curious to know about that!

 

[ste_mc_efc]

I

S.I Unit = farad.

Pffft. the proper SI units are s^4?A^2?m^−2?kg^−1

 

[Pranav]

Pffft. the proper SI units are s^4?A^2?m^−2?kg^−1

We call them dimensional formula/units here in India. Like for Energy the dimensional formula is [ML^2T^-1], the S.I unit is Joule and the C.G.S unit is Erg.

 

[ste_mc_efc]

We call them dimensional formula/units here in India. Like for Energy the dimensional formula is [ML^2T^-1], the S.I unit is Joule and the C.G.S unit is Erg.

Yes they are still SI, just not base SI, which I often have to break compound SI units into to make sure the units actually cancel in equations.

 

[TumTum]

There is also the R-C circuit which are used in radio's and etc for different frequencies.

RC circuit - Wikipedia, the free encyclopedia

 

[Pranav]

Talking of circuits, there is a LCR circuit as well where 'L' stands for an Inductor.

 

[Varun]

Reps to the one who proves it -

"Prove that negative signs cancel each other during division."

 

[Abhas]

(a+b) - (-(-a)+b) = 0

hence proved

 

[ARay]

Pffft. the proper SI units are s^4?A^2?m^−2?kg^−1

I think you are mistaken. That's base units you are talking about

 

[Varun]

(a+b) - (-(-a)+b) = 0

hence proved

Made some changes in the question!

 

[Abhas]

We know,
[(a+b)=(a+b)]

This can be written as:

(a+b)
_____ = 1
(a+b)


Therefore, this must also be true:
[(-1)(a+b)=(-1)(a+b)] - Multiplying both sides by (-1)

which can be written as:

-(a+b)
_______ = 1
-(a+b)


thus,
-(a+b).............(a+b)
_______ = 1 = _______
-(a+b).............(a+b)

Thus, negative signs cancel out.
Hence Proved