(in a vacuum)

{f: acting force between point charges (n), k: electrostatic force constant k = 9.0×10 9n m 2/c 2, Q 1, Q2: electric quantity of two point charges (c), r: distance between two point charges (m), and the direction is in them.

3. Electric field strength: e = f/q (definition formula, calculation formula, field strength has nothing to do with electric field force and electric quantity).

{e: electric field intensity (N/C), which is a vector (electric field superposition principle), and q: quantity of electric charge (c).

4. The electric field formed by vacuum point (source) charge E = kq/R2.

{r: distance of source charge to this position (m ), q: quantity of source charge}

5. The field strength of uniform electric field E = UAB/d.

{UAB: voltage AB (V) between two points, distance D between two points: AB (M) in the field strength direction}

6. electric field f = q * e: f = q * e.

{f: electric field force (n/c)}, q: the amount of charge (c) affected by electric field force, e: electric field strength (N/C)}

7. Potential and potential difference: UAB =φa-φb, UAB = WAB/Q =-δ EAB/Q.

8. Electric field force does work: WAB = Q * UAB = EQ * D.

{{WAB: work done by electric field force when charged body goes from A to B (J), Q: charged amount (C), UAB: potential difference between two points A and B in electric field (V) (work done by electric field force has nothing to do with path), E: uniform electric field strength, D: distance between two points along the direction of electric field strength (M)}

9. Electric potential energy:

EA=q*φA

{ea: electric potential energy (J) of charged body at point A, Q: electric quantity (C), φA:A:A point potential (V}.

10. the change of electric potential energy δ EAB = EB-EA.

{Difference of electric potential energy of charged body from position A to position B in electric field}

1 1. Work done by the change of electric field force and electric potential energy Δ eab =-wab =-q * uab.

(The increment of electric potential energy is equal to the negative value of work done by electric field force)

12. Capacitance c = q/u (definition formula, calculation formula)

{c: capacitance (f), q: electric quantity (c), u: voltage (potential difference between two plates) (v)}

13. the capacitance of parallel plate capacitor c = ε s/4 π KD.

(s: relative area of two plates, d: vertical distance between two plates, ε: dielectric constant)

Common capacitor

14. acceleration of charged particles in electric field (VO = 0):w =δek Δ ek

or

qU=mVt2/2，

Vt=(2qU/m) 1/2

15. Deflection when charged particles enter a uniform electric field at a speed Vo in a direction perpendicular to the electric field (regardless of gravity)

Quasi-flat projection

Vertical electric field direction: uniform linear motion L = VOT (in parallel plates with E=U/d heterogeneous charges: E = U/D)

sports

Parallel electric field direction: uniformly accelerated linear motion with zero initial velocity D = AT2/2, A = F/M = QE/M.

Note: (1) When two identical charged metal balls are in contact, the power distribution law: different kinds of original charges are neutralized first and then evenly divided, and the total amount of the same kind of original charges is evenly divided;

(2) The electric field line starts with positive charge and ends with negative charge. The electric field lines do not intersect, and the tangent direction is the field strength direction. Where the electric field lines are dense, the electric field is strong, and the potential is lower and lower along the electric field lines, which are perpendicular to the equipotential lines.

(3) The electric field line distribution of common electric fields needs to be memorized;

(4) The electric field strength (vector) and electric potential (scalar) are determined by the electric field itself, and the electric field force and electric potential are also related to the electric quantity and the positive and negative charges of the charged body;

(5) In electrostatic balance, the conductor is an equipotential body with an equipotential surface, the electric field line near the outer surface of the conductor is perpendicular to the surface of the conductor, the synthetic field strength inside the conductor is zero, there is no net charge inside the conductor, and the net charge is only distributed on the outer surface of the conductor;

(6) Capacitance unit conversion:1f =106 μ f =10/2 pf;

(7) Electron Volt (eV) is the unit of energy,1EV =1.60×10-19j;

(8) Other related contents: electrostatic shielding.

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Oscilloscope, Oscilloscope and Their Applications

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Equipotential surface/tip discharge, etc.

(9) electric field intensity E=U/d=4πkQ/εS, and work w = u * q.