A uniform electric field and a uniform magnetic field act in the same direction in a region. An electron is projected parallel to those fields. The electron:
Options

Question

A uniform electric field and a uniform magnetic field act in the same direction in a region. An electron is projected parallel to those fields. The electron:

G1 Physics · Accepted Answer

Step 1: The magnetic force is q(v⃗ × B⃗) = 0 for parallel velocity and B. Step 2: Electric force F⃗ = −eE⃗ is opposite to velocity (electron charge is negative). Step 3: Thus the electron slows down initially, and option A is correct. Final answer: (A) will decrease in speed.