Answer:
The following statements are correct.
1. The magnetic force on the current-carrying wire is strongest when the current is perpendicular to the magnetic field lines.
2. The direction of the magnetic force acting on a current-carrying wire in a uniform magnetic field is perpendicular to the direction of the field.
3. The direction of the magnetic force acting on a current-carrying wire in a uniform magnetic field is perpendicular to the direction of the current.
Wrong statements:
1. The magnetic force on the current-carrying wire is strongest when the current is parallel to the magnetic field lines.
Explanation:
Answer:
i)20369 photons
ii) 40 ps
Explanation:
Momentum of one Sodium atom:

In other to stop it, it must absorb the same momentum in photons:

Now, for the minimun time, we use the speed of light and the wavelength. For the n photons:
