Cut It Into Pieces, and Ask What Varies With the Piece

You'll learnhow to find the field of a charged rod: cut it into pieces, give every piece its own distance, and add.

A 10 cm rod carries 60 nC. How hard does it push on a charge 2 cm away? Not the way a point charge would — the shortcut that pretends it does comes out 2.69 times too big. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · CUT INTO PIECES · EVERY PIECE ITS OWN r · CHECK THE LIMITS · v2

every piece gets its own distance · check the answer at both limits

Before you start

What you're looking at

A charged rod, drawn in pink, and a marked field point above it. The bright slice is one little piece of the rod.

The question

How hard does the whole rod push at that point?

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