Question

Which property of a reflecting telescope determines its light-gathering or light-collecting power?
A. Elimination of extraneous light.
B. Size of the primary lens.
C. Obstruction of ultraviolet rays.
D. Apprehending white light better than any other colour.

Answer 1

Hint: A telescope is an instrument that uses lenses, curved mirrors, or a mixture of the 2 to watch distant objects, or various devices that use nonparticulate radiation to look at distant objects through their emission, absorption, or reflection. Refracting telescopes, which used glass lenses and were invented within the Netherlands at the start of the 17th century, were the primary known practical telescopes.

Complete answer:
Within some decades of the primary optical telescope, the optical telescope was invented, which collects and focuses light using mirrors. Many new kinds of telescopes were invented within the twentieth century, including radio telescopes within the 1930s and infrared telescopes within the 1960s. The term "telescope" now encompasses a good range of instruments capable of detecting various regions of the spectrum and in some cases other kinds of detectors.

In comparison to refractors, reflecting telescopes have several other advantages. Because reflected light doesn't disperse in step with wavelength, they're not subject to aberration. A reflector's telescope tube is additionally shorter than that of a refractor of the identical diameter, lowering the tube's cost.

The diameter (or aperture) of an optical telescope's objective (the primary lens or mirror that collects and focuses light) is proportional to its light-gathering power, and therefore the area of the target is proportional to its light-gathering power. The more light the telescope collects and therefore the finer detail it resolves, the larger the target.The size of the first lens is the property of an optical telescope that determines its light-gathering or light-collecting power.

Thus, the solution is option B.

Note: An optical telescope is an astronomical telescope that forms a picture employing a lens as its objective. Refracting telescopes were first employed in spy glasses and astronomical telescopes, but they're now also utilized in long-focus camera lenses.