A convex lens is typically used in applications where light needs to be concentrated or focused. Among the options you provided, the following most likely uses a convex lens:
- Movie projectors
Movie projectors use convex lenses to focus and enlarge images onto a screen. While corrective eyeglass lenses can also be convex, they are specifically designed to correct vision rather than focus light for projection. Therefore, in the context of typical usage involving focusing light, movie projectors are the best choice.
Spotlights can use various types of lenses, and flashlights generally use a concave lens to direct light rather than a convex lens. Binoculars often use a combination of lenses, including convex lenses. So again, movie projectors is the most correct answer.