## Electromagnetic Induction FormulaThe formula for electromagnetic induction are as stated below | ||

Description | Formula | |

Magnetic Flux | The magnetic flux through a plane of area dA placed in a uniform magnetic field B is given as ϕ=∫ B ⃗∙dA ⃗When the surface is closed, then magnetic flux will be zero. This is due to magnetic lines of force are closed lines and free magnetic poles is not exist | |

Electromagnetic Induction: Faraday’s Law | First Law: Whenever magnetic flux linked with a circuit changes with time, an induced emf is generated in the circuit that lasts as long as the change in magnetic flux continues. Second Law: According to this law, the induced emf is equal to the negative rate of change of flux through the circuit. E = –dϕdt | |

Lenz’s Law | The direction of induced emf or current in the circuit is in such a way that it opposes the cause due to which it is produced. Therefore, E = -dϕ/dt | |

Induced emf | Induced emf is given as E = -N(dϕ/dt)E = -N((ϕ_1- ϕ_2)/t) | |

Induced Current | I=E/R = N/R(dϕ/dt)= N/R((ϕ_1- ϕ_2)/t) | |

Self – Induction | Change in the strength of flow of current is opposed by a characteristic of a coil is known as self-inductance. It is given as ϕ=LI Here, L = coefficient of self – inductance Magnetic flux rate of change in the coil is given as Idϕ/dt = L dl/dt=-E | |

Mutual – Induction | Mutual – Induction is given as e_2=(d(N_2 ϕ_2)/dt = M (dl_1)/dtTherefore, M=(μ_0 N_1 N_2 A)/l | |

## Electromagnetic wavesThe formula for electromagnetic waves are as stated below | ||

Description | Formula | |

Gauss’s law for electricity | ∮ E⋅dA=Q/ε_0 Here, E is the electric field, A is the area, Q is the charge and ε_0 is the permittivity of free space. | |

Gauss’s law for magnetism | ∮ B⋅dA=0B is the magnetic field and A is the area. | |

Faraday’s law | ∮ E⋅dl=-(dΦ_B)/dt Here, E is the electric field, l is the length of the conductor, Φ_B is the magnetic flux and t is the time. | |

Ampere- Maxwell law | ∮ B⋅dl=μ_0 i+μ_0 ε_0 (dΦ_B)/dt Here, B is the magnetic field, l is the length of the conductor, μ_0 | |

Speed of light in vacuum | c=1/√(μ_0 ε_0 ) | |

## Electrostatics formulaThe formula for electrostatistics are as stated below | ||

Description | Formula | |

Electrostatic force between two-point charges |
F=1/4Π∈ q1q2/r2 r Here, ε_0 | |

Electric field | E ⃗=F ⃗/q_0 Here, F is the electrostatic force experienced by test charge q0. | |

Electric field due to a uniformly charged ring | E_axis=KQx/(R^2+x^2 )^(3/2) Here, K is the relative permeability, Q is the charge on the ring, x is the perpendicular distance from the ring to the point at which the electric field is to be calculated and R is the radius of the ring. | |

Electric field due to a uniformly charged disc | E=σ/(2ε_0 ) [1-x/√(R^2+x^2 )] Here, σ is the surface charge density, ε_0is the permittivity of free space, x is the perpendicular distance from the centre of the disk and R is the radius of the disk. | |

Work done by external force | The work done by an external force in bringing a charge q from potential V_Bto V_A is: W=q(V_A-V_B )̂ | |

Electrostatic potential energy | U=qV Here, q is the charge and V is the potential. | |

Electrostatic energy | U=1/(4πε_0 ) (q_1 q_2)/r here q1q2 are the charges and r is the distance between the charges. | |

Electric potential at a point due to a point charge | V=1/(4πε_0 ) q/r | |

Dipole moment | The formula for calculating electric dipole moment is p ⃗=qd ⃗Here q is the magnitude of the charge and d is the distance between the charges. | |

Potential at a point due to dipole | The potential at a point due to a dipole is given as: V=1/(4πε_0 ) (p cos θ )/r^2Here, p is the dipole moment and θ is the angle made by the line joining the point and the centre of the dipole with the line joining the charges and r is the distance from the point at which the potential is to be calculated and the line joining the charges. | |

Torque experienced by dipole due to electric field | τ ⃗=p ⃗×E ⃗ here, p is the dipole moment and E is the electric field. | |

## Friction formulaThe formula for friction are as stated below | ||

Description | Formula | |

Force due to kinetic friction | The formula for calculating the force due to kinetic friction is: F_k=μ_k R here, F_k is the force due to kinetic friction, μ_k is the coefficient of kinetic friction and R is the normal reaction force on the body on which the force is acting. If the body is lying on levelled plane, then the normal force is given as: R=mg Here m is the mass and g is the gravitational acceleration. When the body is lying on a plane that is at some angle with the horizontal then the normal reaction force on the body is given as: R=mgcosθ | |

Force due to static friction | The formula for calculating the force due to static friction is: F_s=μ_s R here, Fs is the force due to static friction, μ_s is the coefficient of static friction and R is the normal reaction force on the body. |

# JEE Physics Important Formulas Part -4

In this article we will go through physics quick formula revision for JEE 2022. Find the important formulas of Electromagnetic Induction, Electromagnetic waves, Electrostatics and Friction.