A particle of charge −2 μC moves in a magnetic field of 2 T directed along the positive y-axis. Its velocity is (2î + 2ĵ) × 10⁶ m/s. Find the magnetic force on it.

Question

G1 Physics · Accepted Answer

Step 1: Magnetic Lorentz force is F⃗ = q(v⃗ × B⃗). Step 2: Given q = −2 × 10⁻⁶ C, v⃗ = (2î + 2ĵ) × 10⁶ m/s and B⃗ = 2ĵ T. Step 3: v⃗ × B⃗ = (2 × 10⁶ î) × (2ĵ) = 4 × 10⁶ k̂ (m T/s). Step 4: F⃗ = (−2 × 10⁻⁶)(4 × 10⁶ k̂) = −8k̂ N. Final answer: (A) 8 N in the negative z-direction.