A telescope that uses two convex lenses to form images.

• A. Refracting telescope
• B. Refracting (telescope)
• C. Reflecting telescope
• D. Radio telescope

Answer: (B)

A telescope that uses two convex lenses to form images is a refracting telescope. Light enters through the objective lens, which bends (refracts) and brings rays to a focus to form a real image at the focal plane. The eyepiece lens then acts as a magnifier, enlarging that real image so you can see more detail. The whole system relies on refraction through glass, which is why this type is called refracting. This differs from a reflecting telescope, which uses mirrors to gather and focus light, and from a radio telescope, which detects radio waves with a dish rather than visible lenses.