A uniform electric field and a uniform magnetic field are acting along the positive x-axis in a certain region. A proton is projected into this region with its initial velocity directed along the negative x-axis. Which of the following best describes the subsequent motion of the proton?

Step-by-step solution

The magnetic force on the proton is F _m = q( v B ) . Since the velocity is anti-parallel to the magnetic field ( = 180^ ), the magnetic force is zero. Thus, the magnetic field does not change the path of the proton. The electric force on the positively charged proton is F _e = q E , which acts in the direction of the electric field (positive x-axis). Since the proton is moving along the negative x-axis, the electric force acts opposite to its direction of motion. Therefore, the proton experiences a retarding force