Law of conservation of mechanical energy: mgh1+mv12/2 = mgh2+mv22/2.

The mathematical expression of Coulomb's law: F=kQq/r2.

Definition of electric field strength: e = f/q.

Definition of potential difference: u = w/q.

Ohm's law: I = u/r.

Calculation of electric power: P=UI.

Joule's law: Q=I2Rt.

Definition of magnetic induction intensity: B=F/IL.

The formula of ampere force is F=BIL.

The formula of Lorentz force: f=qvb.

Faraday's law of electromagnetic induction: e = Ф Ф/Ф t.

Induced electromotive force generated by conductor cutting magnetic induction line: E=Blv.

Common methods of physics multiple-choice questions:

① Screening (elimination) method: According to the information in the topic and the knowledge you have, from easy to difficult, gradually eliminate unreasonable options and finally approach the correct answer.

② Special value (special case) method: let some physical quantities take special values and make judgments through simple analysis and calculation. Only applicable to multiple-choice questions that can exclude the rest of the wrong options after substituting special values in each option.

(3) Limit analysis method: a method that limits some physical quantities and draws conclusions.