Archimede's principle states that the buoyant force acting on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. In other words, the magnitude of the buoyant force can be determined by Archimede's principle.

Explanation:
- When an object is immersed in a fluid, it experiences an upward force called the buoyant force. This force is exerted by the fluid on the object and is equal to the weight of the fluid displaced by the object.
- The weight of the fluid displaced by the object is directly proportional to the volume of the fluid displaced. This means that the more fluid the object displaces, the greater the buoyant force will be.
- The magnitude of the buoyant force can be determined by the formula:
Buoyant force = Weight of the fluid displaced = ρ * V * g
where ρ is the density of the fluid, V is the volume of the fluid displaced, and g is the acceleration due to gravity.
- From this formula, it is clear that the magnitude of the buoyant force depends on the density of the fluid and the volume of the fluid displaced by the object.
- The density of the fluid is a property of the fluid itself and can be determined experimentally or through other means.
- The volume of the fluid displaced by the object is determined by the size, shape, and position of the object in the fluid.
- By applying Archimede's principle, we can calculate the buoyant force acting on an object by determining the weight of the fluid displaced, which is equal to the buoyant force.
- Therefore, Archimede's principle is the correct option for determining the magnitude of the buoyant force.