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Electromagnetic Induction formula sheet

Every formula in the Electromagnetic Induction chapter for JEE Main, with one line on when it applies. Topic 1 is open to everyone; sign in free to read all 24 and download the PDF.

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How we count: 7× asked means 7 past JEE Main questions in the PrepWiser bank needed that formula, and "last" is the latest year one appeared. ★ marks formulas asked 8 or more times.

Flux and Faraday's law

Magnetic flux
8× asked, last 2026
Φ=B⃗⋅A⃗=BAcos⁡θ\Phi=\vec B\cdot\vec A=BA\cos\theta
θ\theta from the normal; 1 Wb = 1 T m2^2. Only BB along the normal counts.
Faraday's law
21× asked, last 2026
e=−NdΦdt,∣eavg∣=N∣ΔΦ∣Δt,I=eRe=-N\frac{d\Phi}{dt},\qquad |e_{\text{avg}}|=N\frac{|\Delta\Phi|}{\Delta t},\qquad I=\frac eR
Minus sign = Lenz. Changing area: e=B dA/dte=B\,dA/dt; circle: 2πrB dr/dt2\pi rB\,dr/dt.
Sinusoidal field through a loop
B=B0sin⁡ωt ⇒ emax⁡=NB0ωAcos⁡θB=B_0\sin\omega t\ \Rightarrow\ e_{\max}=NB_0\omega A\cos\theta
Loop in a solenoid: emax⁡=μ0nI0ωAe_{\max}=\mu_0nI_0\omega A. Wider ring: only the solenoid's area links flux.
Induced charge
1× asked, last 2023
Δq=N∣ΔΦ∣R\Delta q=\frac{N|\Delta\Phi|}R
Independent of speed. Reversed field: ΔΦ=2BA\Delta\Phi=2BA.
Heat in the loop
8× asked, last 2026
P=e2R,H=∫e2R dt,R=ρlπr2P=\frac{e^2}R,\qquad H=\int\frac{e^2}R\,dt,\qquad R=\frac{\rho l}{\pi r^2}
Coil in a changing field: II independent of NN; P∝NA3/2r2P\propto NA^{3/2}r^2. 1 G =10−4=10^{-4} T.

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19 more formulas in 4 topics

Lenz's law and eddy currents, Motional emf and the AC generator, Self-inductance and Mutual inductance. Read the first part free. Sign in free with Google to read the rest and download the PDF.

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Lenz's law and eddy currents

  • Lenz's law5×
  • Eddy currents2×

Motional emf and the AC generator

  • Rod moving in a field12×
  • Rod near a long wire
  • Rod on rails5×
  • Inclined rails, vertical field
  • Loop pulled out of a field
  • Loop crossing a field edge5×
  • Rotating rod and disc8×
  • Earth's field components6×
  • AC generator11×

Self-inductance

  • Self-inductance15×
  • LR circuit
  • Long solenoid3×
  • Energy in an inductor10×

Mutual inductance

  • Mutual inductance5×
  • Long wire and coplanar rectangle
  • Coaxial solenoids2×
  • Small loop at a large loop's centre8×

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About 120 past JEE Main questions from this chapter, with instant answer checking and step-by-step solutions where available. Free, and you can start without signing up.

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