Light and Telescopes

When light passes through a prism of glass,

• the prism absorbs colors from different parts of the broad beam coming out of the prism, leaving the complementary colors that we see.
• different colors are caused by multiple reflections within the prism and the resulting interference between the beams.
• refraction changes the directions of different colors or wavelengths of light.
• the prism adds colors to different parts of the outgoing and broadly scattered beam.

All forms of light have what property in common?

• All are electromagnetic radiation.
• All have the same wavelength.
• All are ultrasonic radiation.
• All have wavelengths between 400 nm and 700 nm.

The speed of light is

• 3 × 10^10 m/sec.
• 3 × 10^8 m/sec.
• 3 × 10^12 m/sec.
• 3 × 10^5 m/sec.

Who first showed that light does not travel at infinite speed?

• Ole Rømer in 1675
• Thomas Young in 1801
• James Clerk Maxwell in 1864
• Isaac Newton in 1704

What is the one fundamental difference between X rays and radio waves?

• They always come from different sources.
• Their wavelengths are very different.
• Their speeds in outer space are different.
• Radio waves are always wavelike, whereas X rays always behave like particles.

Which of the following lists of different types of electromagnetic radiation is correctly ordered in wavelength, from shortest to longest?

• Gamma rays, ultraviolet, radio, infrared
• Radio, ultraviolet, infrared, gamma rays
• Radio, infrared, ultraviolet, gamma rays
• Gamma rays, ultraviolet, infrared, radio

A Newtonian telescope uses

• only one mirror with its front surface shaped into a parabola.
• one curved mirror and one flat mirror at a 45° angle to the first mirror axis.
• two flat mirrors inclined to each other at a right angle.
• two curved mirrors, one convex, the second concave in shape.

The light-gathering power of a telescope is directly dependent on

• the area of the final aperture of its eyepiece.
• the focal length of its primary mirror or lens.
• the ratio of the focal lengths of its primary element (mirror or lens) and its eyepiece.
• the area of its primary mirror or lens.

A refracting telescope is the type that uses, as its main optical element,

• a lens.
• a prism of glass.
• a combination of many small plane mirrors.
• a mirror.

Chromatic aberration is the failure of a telescope objective to bring all colors of light to the same focus and appears

• only in a reflecting telescope.
• in both reflecting and refracting telescopes.
• in all telescopes because it is caused by a basic property of light.
• only in a refracting telescope.