Optics

Red light has the longest wavelength among the visible spectrum colors listed, so it is deviated least when passing through a prism or similar medium due to less refraction compared to shorter wavelengths like blue or violet.

The refractive index is a ratio of the speed of light in vacuum to the speed of light in the medium, making it a dimensionless quantity with no units.

Refraction of sound occurs when sound waves pass from one medium to another or when there is a variation in temperature or density within a medium, causing the sound waves to bend. Since both water and air can cause such refraction, the correct answer is 'Both A & B'.

A dioptre is a unit of measurement for the optical power of a lens or curved mirror, defined as the reciprocal of the focal length measured in meters. It is not related to luminous intensity, general power, or astronomical distances.

A dioptre is the unit of measurement for the optical power of a lens or curved mirror, which is the reciprocal of the focal length measured in meters. Therefore, it measures lens refractive power.

Stars appear to twinkle because their light passes through Earth's turbulent atmosphere, causing the light to refract multiple times and change direction slightly, which makes the stars seem to flicker or twinkle.

A spectroscope is an optical instrument used to measure the properties of visible light by separating it into its component wavelengths or spectrum. This allows analysis of the light's properties, unlike microscopes, telescopes, or oscilloscopes which serve different purposes.

A rainbow is formed due to the combined effects of refraction (bending of light entering water droplets), dispersion (splitting of light into colors), and total internal reflection (light reflecting inside the droplet). Hence, all these phenomena are involved.

The magnifying power of a simple microscope is inversely proportional to the focal length of its lens. Decreasing the focal length increases the angular magnification, thus increasing the magnifying power.

To see her full image in a plane mirror, the minimum length of the mirror must be half her height, which is 3 feet for a 6 feet tall lady. This is because the angles of incidence and reflection allow the full image to be seen in a mirror half the person's height.

Myopia, or nearsightedness, occurs when the eye focuses images in front of the retina. It is corrected using a concave lens, which diverges light rays so they focus correctly on the retina.

Twinkling of stars occurs due to the refraction of starlight as it passes through the Earth's turbulent atmosphere, causing the light to bend and vary in intensity and position.

Ole Rømer was the first scientist to successfully measure the speed of light in 1676 by observing the timing variations of eclipses of Jupiter's moon Io, demonstrating that light has a finite speed.

Light is guided through the core of an optical fiber due to total internal reflection, which occurs when light traveling within the core hits the core-cladding boundary at an angle greater than the critical angle, causing it to reflect back into the core.