What principle is applied in a gear system to transmit power?

In a gear system, power transmission relies fundamentally on mechanical advantage achieved through gear ratios. When gears mesh, they convert input rotational speed and torque into a different output speed and torque depending on their sizes and the relationship between them.

The gear ratio defines how many rotations a driving gear makes compared to the gear it drives. For example, if a small gear drives a larger gear, the larger gear will rotate slower but with greater torque. This ratio is essential for various applications, whether for increasing speed or enhancing torque, enabling machines and vehicles to operate efficiently under varying loads or speeds.

The other options do not effectively capture the primary mechanism of power transmission in gear systems. Friction does play a role in gear operation but is not the principle by which power is transmitted; rather, it is often a factor that affects efficiency. Weight distribution concerns the physical support and balance of the system but is not a principle of power transmission. Lastly, magnetic fields are not a component of typical mechanical gear systems, as they rely on physical contact and mechanical interaction between gears instead.