Current Electricity
Class 12 · Current Electricity

Short Circuit

R_load → 0. I = ε/r. Wire overheats — visualized with red glow.

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Key Notes

01

When R_load → 0, current spikes to I_short = ε/r.

02

All energy is dissipated in r → wire heats rapidly, can melt or catch fire.

03

Why fuses, MCBs, and circuit breakers exist.

Formulas

Short-circuit current

Limited only by internal R.

Power on r

Maximum heating in cell.

Important Points

Practical batteries can deliver very high short-circuit currents — dangerous.

Modern Li-ion has built-in protection circuits to prevent shorts.

Short Circuit notes from sciphylab (also known as SciPhy, SciPhy Lab, SciPhy Labs, Physics Lab). Class 12 physics revision for JEE Mains, JEE Advanced, NEET UG, AP Physics 1/2/C, SAT, and CUET-UG.