A proton enters a region of magnetic field as shown - Scottish Highers Physics - Question 10 - 2022

To determine the direction of the force on the proton as it enters the magnetic field, we can apply the right-hand rule. This law states that if you point your thumb in the direction of the velocity of the positive charge (proton) and your fingers in the direction of the magnetic field, your palm will face the direction of the force.

1. The proton moves into the magnetic field, which is directed from the left to the right.
2. Therefore, if your thumb is pointing in the direction of the proton's velocity (into the page), and your fingers point from left to right (the direction of the magnetic field), your palm will face out of the page.

Thus, the correct answer is: A: out of the page.