Rainbow Colors Order Online Test (General Knowledge) Updated

The rainbow is one of nature’s most beautiful and scientifically fascinating phenomena, and questions about its colours, order, formation, and related optical science are a regular feature in Pakistan’s most competitive examinations, including CSS (Central Superior Services), PMS (Provincial Management Services), NTS (National Testing Service), PPSC (Punjab Public Service Commission), FPSC (Federal Public Service Commission), SPSC, and KPPSC. Questions on rainbows appear in General Science, General Knowledge, and Current Affairs sections, covering facts such as the correct order of colours in a rainbow, the physics of light dispersion and refraction, the role of water droplets, the difference between primary and secondary rainbows, famous scientists who explained the rainbow, the mnemonic ROYGBIV, wavelengths of visible light, and rare rainbow types. A firm grasp of this topic ensures easy marks in the science section of any competitive exam. This specially curated MCQ set for GoTest.com.pk covers every important angle — the order of colours, scientific explanations, wavelength rankings, historical discoveries, types of rainbows, and fun facts about this natural wonder. Each question is followed by a detailed explanation to help you understand not just the correct answer but also the broader context. Students are strongly advised to read every explanation carefully even after getting the right answer, as exam papers often twist familiar facts. Consistent practice with these MCQs will sharpen your recall and improve your confidence for exam day.

Rainbow Colors Order Online Test (General Knowledge) Updated

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1. What is "dispersion" of light in the context of rainbows?

The absorption of certain colours of light by water

The reflection of light off a flat water surface

The spreading of light across a large area

The separation of white light into its component colours due to different wavelengths bending by different amounts

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2. What is "Alexander's Band" in the context of rainbows?

The colourless band at the very centre of a rainbow

A band of extra-bright light at the top of a rainbow

A rainbow that appears as a straight horizontal band

The dark region of sky between the primary and secondary rainbow

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3. Which colour of light has the longest wavelength in the visible spectrum?

Violet

Blue

Red

Green

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4. What is a "lunar rainbow" (moonbow)?

A rainbow visible only through a telescope

A rainbow that only appears during a solar eclipse

A rainbow that appears on the Moon's surface

A rainbow formed by moonlight instead of sunlight, usually appearing white or faint

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5. What physical phenomenon causes a rainbow to form?

Reflection of sunlight off cloud surfaces

Diffraction of sunlight around clouds

Absorption of sunlight by moisture in the air

Refraction, reflection, and dispersion of sunlight through water droplets

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6. Which colour of the rainbow has the lowest frequency?

Blue

Green

Red

Violet

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7. Why does a rainbow appear as an arc rather than a full line or irregular shape?

Because the Earth's curvature bends the light into an arc

Because raindrops only form in curved patterns in the atmosphere

Because all raindrops that send the correct wavelength of light to the observer's eye lie on a cone of approximately 42 degrees centred on the anti-solar point

Because clouds are curved

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8. What is the colour of the sky between the primary and secondary rainbow called?

Descartes' Band

Rainbow shadow

The neutral zone

Alexander's Dark Band

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9. What is the correct order of colours in a secondary rainbow from top to bottom?

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Orange, Red, Violet, Indigo, Blue, Green, Yellow

Green, Blue, Indigo, Violet, Red, Orange, Yellow

Violet, Indigo, Blue, Green, Yellow, Orange, Red

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10. Which colour appears at the top (outermost arc) of a primary rainbow?

Red

Yellow

Blue

Violet

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11. How does the size of raindrops affect the appearance of a rainbow?

Raindrop size has no effect on rainbow appearance

Only medium-sized droplets can produce rainbows at all

Larger raindrops produce brighter, more vivid rainbows with well-defined colour bands; very small droplets produce white or pale fogbows

Larger raindrops produce fainter rainbows; smaller drops produce brighter ones

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12. What is a "glory" in atmospheric optics, related to rainbow phenomena?

A small, circular, rainbow-like ring of colours seen around the shadow of the observer's head on clouds or fog below

A bright halo around the full Moon

Another name for a double rainbow

The brightest point at the top of a rainbow arc

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13. Why can two people standing side by side never see exactly the same rainbow?

Because rainbows form at different distances for each observer

Because one person may be taller, changing the angle

Because each observer sees light reflected from different sets of raindrops at their own specific anti-solar point

Because their eyes have different sensitivities to colour

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14. What is the approximate wavelength of green light in the visible spectrum?

450-495 nm

495-570 nm

620-750 nm

380-450 nm

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15. What is a "secondary rainbow" and how does it differ from a primary rainbow?

A second rainbow of identical appearance that forms simultaneously with the primary

A rainbow that appears only at night

A larger, fainter rainbow outside the primary rainbow with the colour order reversed

A smaller rainbow that appears inside the primary rainbow with the same colour order

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16. What is an "infrared rainbow"?

A rainbow created by infrared heaters used in industry

A rainbow that appears only in very hot desert climates

A rainbow formed by infrared radiation just beyond the red end of the visible spectrum, detectable only by infrared cameras

A rainbow visible only with special goggles

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17. What is the phenomenon where a rainbow appears to move as you move toward it?

Rainbow displacement

The rainbow always remains at a fixed angular distance from the observer's anti-solar point, so it appears to move with the observer

Atmospheric refraction shifting the rainbow's position

The rainbow reflects off moving rain clouds

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18. What is a "rainbow" in simple scientific terms?

A stream of pure white light reflected off rain clouds

A permanent atmospheric feature visible after every rainfall

A meteorological and optical phenomenon producing a spectrum of light in the sky caused by sunlight interacting with water droplets

A reflection of sunlight off a wet ground surface

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19. What are "supernumerary rainbows"?

Rainbows with more than seven colours

Rainbows that appear above the primary arc

Rainbows visible only through binoculars

Faint additional arcs of colour that appear just inside the primary rainbow

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20. What is a "double rainbow" and what is special about it?

Two rainbows side by side at the same angle

A primary and secondary rainbow appearing simultaneously, with the secondary showing reversed colours

A rainbow reflected in a lake creating the illusion of two rainbows

A rainbow with double the number of colours

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21. Why is a rainbow always seen in the direction opposite the Sun?

Because clouds block sunlight from the same direction as the Sun

Because the atmosphere bends all light to the opposite side of the sky

Because raindrops only form on the shadowed side of the sky

Because rainbows are formed by light reflecting inside raindrops and returning toward the light source — back toward the observer facing away from the Sun

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22. What are the three primary colours of pigment (subtractive colour model)?

Red, Green, Blue

Red, Yellow, Blue (traditional art) or Cyan, Magenta, Yellow (printing)

Orange, Green, Violet

White, Grey, Black

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23. What is the name of the book in which Isaac Newton presented his theory of light and colours including his work on the spectrum?

Principia Mathematica

Discourse on Method

Opticks

The Colour of Light

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24. What is the speed of light in water compared to its speed in air?

Faster in water than in air

The same in both water and air

Slower in water than in air

Depends on the colour of light — some faster, some slower

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25. How many colours are there in a rainbow?

6

5

7

8

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26. Why does indigo appear as a separate colour in the traditional rainbow listing despite being difficult for many people to distinguish from blue and violet?

Because it was discovered as a separate colour after the other six

Because indigo refracts at a uniquely different angle from blue and violet

Because Isaac Newton chose to include it to make the total seven colours, matching the number of musical notes and days of the week

Because it has a unique chemical composition different from blue

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27. Which colour of light has the shortest wavelength in the visible spectrum?

Violet

Green

Red

Blue

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28. What is a "fogbow"?

Another name for a secondary rainbow

A rainbow seen only in coastal foggy areas

A rainbow that appears in fog rather than rain, usually appearing white or very faint

A rainbow formed by artificial fog machines

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29. What is a "twinned rainbow"?

A rainbow and its reflection in water appearing as twins

A primary and secondary rainbow of equal brightness

Two separate rainbows that cross each other

A single rainbow that splits into two arcs from a common base

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30. What is "Roy G. Biv"?

A unit of measurement for light wavelength

A mnemonic device personifying the colours of the rainbow: Red, Orange, Yellow, Green, Blue, Indigo, Violet

The name of the scientist who discovered the rainbow spectrum

A type of spectrometer used to study rainbow colours

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31. Which colour appears at the bottom (innermost arc) of a primary rainbow?

Violet

Red

Indigo

Orange

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32. What colours are produced when red and blue light are combined?

Yellow

Cyan

Magenta (pink)

Green

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33. At what time of day is a rainbow most likely to be visible?

Only during overcast conditions with no direct sunlight

At night during a full Moon

In the early morning or late afternoon when the Sun is low on the horizon

At midday when the Sun is highest

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34. What is the "visible spectrum" of light?

The light visible only through a spectrometer

All electromagnetic radiation including X-rays and radio waves

The colours visible only in a rainbow

The range of electromagnetic wavelengths (approximately 380-750 nm) that the human eye can detect as colour

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35. Which colour of the rainbow has the highest frequency?

Red

Violet

Orange

Green

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36. What is the correct order of colours in a rainbow from top to bottom?

Blue, Green, Yellow, Orange, Red, Indigo, Violet

Red, Yellow, Orange, Green, Blue, Violet, Indigo

Violet, Indigo, Blue, Green, Yellow, Orange, Red

Red, Orange, Yellow, Green, Blue, Indigo, Violet

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37. What is the correct order of colours in a rainbow from the innermost to the outermost arc?

Green, Blue, Indigo, Violet, Red, Orange, Yellow

Violet, Indigo, Blue, Green, Yellow, Orange, Red

Blue, Green, Yellow, Orange, Red, Indigo, Violet

Red, Orange, Yellow, Green, Blue, Indigo, Violet

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38. What is "white light" and how is it related to rainbow colours?

White light only contains red, green, and blue

White light is light that has had all colours removed

White light is a mixture of all colours of the visible spectrum combined together

White light is pure light with no colour component

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39. Which colour of the rainbow is associated with a wavelength of approximately 580 nanometres?

Yellow

Blue

Orange

Green

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40. Which scientist first mathematically explained the geometry of rainbow formation?

Isaac Newton

Aristotle

Snell

Rene Descartes

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41. What is the role of the "anti-solar point" in rainbow formation?

The point in the sky where sunlight is completely blocked

The point where the rainbow touches the ground

The position of the Moon during a lunar rainbow

The point directly opposite the Sun from the observer's position — the centre of the rainbow circle

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42. What is a "rainbow" in folklore and cultural symbolism?

A symbol of the four seasons of the year

A sign of forthcoming heavy rainfall

A symbol of hope, promise, good fortune, and the bridge between earth and the divine in many cultures

A warning sign for sailors of dangerous storms

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43. What is the colour order in a rainbow produced by a prism?

Reversed compared to a natural rainbow — Violet at top, Red at bottom

Prisms produce white light, not a spectrum

Same as a natural rainbow — Red, Orange, Yellow, Green, Blue, Indigo, Violet

Differs from a natural rainbow — prisms show only three colours

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44. What is "refraction" of light?

The bending of light as it passes from one medium to another of different density

The bouncing of light off a surface

The scattering of light in all directions

The absorption of light by a coloured surface

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45. Can a rainbow ever form a complete circle?

No — rainbows are always semicircles

No — the physics of light prevent circular formation

Yes — a full circular rainbow can be seen from an aircraft or high elevation when conditions are right

Yes — but only during a lunar rainbow at night

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46. What is the approximate angle of a primary rainbow as seen from the observer?

20-25 degrees from the anti-solar point

50-55 degrees from the anti-solar point

40-42 degrees from the anti-solar point

60-65 degrees from the anti-solar point

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47. What is a "fire rainbow" or "circumhorizontal arc"?

A rainbow seen only in desert regions during extreme heat

A rainbow caused by wildfires reflecting light through smoke

A rare optical phenomenon forming a colourful horizontal arc in ice-crystal clouds

A rainbow produced by the light of a volcanic eruption

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48. What is the "refractive index" of water and why is it important in rainbow formation?

Approximately 1.33 — meaning light bends as it enters water, enabling dispersion

It varies with rainfall intensity and is not fixed

Approximately 2.5 — causing very strong bending

1.0 — same as air, meaning no bending occurs

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49. What is the popular mnemonic used to remember the order of colours in a rainbow?

ROYGBIV

VIBGYOR

BVIGYOR

GYBIVRO

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50. In which direction should you look to see a rainbow in the morning?

South

North

West (away from the rising Sun)

East (toward the rising Sun)

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51. What is "VIBGYOR" and when is it used?

An alternative name for the secondary rainbow

A formula for calculating rainbow angles

The reverse mnemonic for rainbow colours from bottom to top — Violet, Indigo, Blue, Green, Yellow, Orange, Red

A type of spectrometer used to study rainbow colours

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52. Which scientist is credited with explaining the formation of the rainbow using a prism and the dispersion of white light?

Galileo Galilei

Isaac Newton

Rene Descartes

Albert Einstein

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53. In which of Newton's famous experiments did he demonstrate that white light is composed of all colours?

The gravity well experiment

The prism experiment — passing sunlight through a glass prism in a darkened room

The telescope experiment

The apple falling experiment

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54. What causes the sky inside a primary rainbow (below the arc) to appear brighter?

Direct sunlight reflecting off raindrops toward the observer

The rainbow itself emitting light downward

Light from raindrops inside the primary rainbow arc being reflected back toward the observer at multiple angles

The ground reflecting sunlight back into the sky

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55. What are the three primary colours of light (additive colour model)?

Orange, Green, Violet

Red, Yellow, Blue

Cyan, Magenta, Yellow

Red, Green, Blue

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56. What happens to light when it is "totally internally reflected" inside a raindrop?

The light is converted into heat energy

The light reflects off the inside surface of the raindrop without escaping, directing it back out through the front of the droplet

The light passes straight through without bending

The light is completely absorbed by the water

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