^ best physics teacher for neet on youtube - KP Physics

^Capacitance

December 23, 2021/in Back end /by kp-web-admin

Capacitance

1. Capacitance of a system is a measure of the its capacity to hold charge for a given potential difference.

2. Capacitance can be defined as

3. Capacitance is defined even if a capacitor is neutral.

4. SI unit of capacitance is Farad (F).

5. 1F = 1 C V – 1 = 9 x 10¹¹ stat farad.

6. Farad is a too big unit. Practical capacitors are of the order of mF, nF & pF etc.

7. Generally the two plates have equal and opposite charges. Even if, we give different charges to the plates then the inner surfaces facing each other posses equal and opposite charges.

8. The plates are separated by a distance much smaller than dimensions of a capacitor.

^Rules for writing units

December 23, 2021/in Back end /by kp-web-admin

^Rules for writing units

The initial letter of a unit symbol named after a scientist is written in capital letters, however the full name begins with small letter. e.g. five newtons should be written as 5 N or 5 newtons but not as 5 n.
Symbols for various units are never used in plural form. e.g. 5 N should be written as 5 N and not as 5 Ns, however we can write 5 newtons but not 5 Newtons.
Symbols are never followed by a full stop.
Not more than one solidus is used. e.g. Nm^{– 2}s^{– 1}shouldn’t be written as N/m²/s.
The use of double prefix is avoided, when single prefix is available. e.g. instead of writing μμN we should write pN.

In calculations the prefix is attached with the numerator and not with the denominator.

*The Seven Fundamental Quantities

December 23, 2021/in Back end /by kp-web-admin

*The Seven Fundamental Quantities

^Gauss’s law

December 23, 2021/in Back end /by kp-web-admin

Gauss’s law

1. According to Gauss’s law the electric fluxthrough any arbitrary closed surface in a medium is equal to the total charge enclosed by the that surface divided by the permittivity of that medium. i.e.

2. If medium is air or vacuum, then

3. Gauss’s law is based on the inverse square dependence on distance contained in the Coulomb’s law. Any violation of Gauss’s law will indicate departure from the inverse square law.

4. Using Gauss law we can say no. of electric line of force originating or terminating on a charge of q coulomb is equal to q/ε₀.

^For infinite line charge

December 23, 2021/in Back end /by kp-web-admin

For infinite line charge

Both α & β will approach to 90⁰ & E becomes

^Equipotential surfaces

December 23, 2021/in Back end /by kp-web-admin

Equipotential surfaces

An equipotential surface is an imaginary surface on which every point has one and the same value of electric potential. It can be curved or plane surfaces.
No work is done in moving any charge over an EPS.
Electric field is always ⊥ to EPS.
EPS tells us about direction of electric field.
EPS helps to distinguish regions of strong field from that of weak field. As the separation between two equipotential surfaces is more, where the field is weak & vice – versa.
No EPS can intersect each other.