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When an electron and a proton are placed in an electric field ______.

Asked in GSEB Board July 2017 · Deflection and projectile motion

Answer: (2) only the magnitudes of the forces are the same

Step-by-step solution

Given: an electron (charge -e, mass mₑ) and a proton (charge +e, mass mₚ) in the same field ⃗E.

Idea: the force is ⃗F = q⃗E and the acceleration is ⃗a = (q⃗E)/m.

Forces: |⃗F| = eE on both, but in opposite directions, because the charges have opposite signs.

Accelerations: aₑ = (eE)/(mₑ) and aₚ = (eE)/(mₚ); since mₚ ≈ 1836 mₑ, the electron's is about 1836 times larger, and the two point opposite ways.

So only the magnitudes of the forces are the same.

Why the other options are wrong

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