Newton's theory of Light (2022)

3.1 Newton’s crucial experiment

The English natural philosopher Isaac Newton bought his first prism in 1666, one year after Francesco Grimaldi’s work on diffraction was published.[1]Newton claimed that Grimaldi’s diffraction was simply a new kind of refraction. He argued that the geometric nature of the laws of reflection and refraction could only be explained if light is made of particles, which he referred to as corpuscles, as waves don’t tend to travel in straight lines.

After joining the Royal Society of London in 1672, Newton stated that the 44th trail in a series of experiments he had previously conducted proved that light is made of particles and not waves.[2,3]

Advocates of the wave theory had previously stated that light waves are made of white light and that the colour spectrum that can be seen through a prism is formed because of corruption within the glass. This means that the more glass the light travels through, the more corrupt it will become.

To prove that this was false, Newton passed a beam of white light through two prisms, which were held at such an angle that it split into a spectrum when passing through the first prism and was recomposed, back into white light, by the second prism (as shown in Figure 3.1). This showed that the colour spectrum is not caused by glass corrupting the light. Newton claimed this was a ‘crucial experiment’.

A crucial experiment is an experiment that is devised to decide between two contradictory theories, where the failure of one determines the certainty of the other. Since almost everyone agreed that light must be composed of either particles or waves, Newton used the failure of the wave theory to prove that light is made of particles. Newton concluded that light is composed of coloured particles that combine to appear white.[4]

Newton's theory of Light (1)

Figure 3.1
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(Video) Physics - Newton's corpuscular theory of light - Science

Newton’s crucial experiment.

3.2 Newton’s colour spectrum

Newton introduced the term ‘colour spectrum’ and although the spectrum appears continuous, with no distinct boundaries between the colours, he chose to divide it into seven: red, orange, yellow, green, blue, indigo, and violet. Newton chose the number seven because of the ancient Greek belief that seven is a mystical number.[5]

Newton showed that every colour has a unique angle of refraction that can be calculated using a suitable prism. He saw that all objects appear to be the same colour as the beam of coloured light that illuminates them, and that a beam of coloured light will stay the same colour no matter how many times it is reflected or refracted. This led him to conclude that colour is a property of the light that reflects from objects, not a property of the objects themselves.[2]

3.3 Criticism from the Royal Society

Despite Newton’s confidence that his theory had been proven, it still faced several problems and was not accepted straight away. Within a year of his announcement, fellow Royal Society member, the English natural philosopher Robert Hooke, published similar results to Grimaldi. He argued that diffraction is not a new type of refraction, as Newton had claimed, and that it could only be explained by assuming that light is composed of waves.[1,6]

Many other members joined Hooke in criticising Newton’s particle theory. Some denied that Newton’s colour spectrum existed at all and others denied that his 44th trial really proved that light is not composed of waves. Those that tried to replicate Newton’s experiment often failed.

Prisms were still not commonly accepted as scientific instruments. They were sold as simple forms of entertainment, and there was little technical work on their design or improvement. Venetian glass was regarded as the standard against which other glasses were compared but even this was full of air bubbles and flaws. Newton did not help matters by concealing the details of his trials. He did not explain how to produce a spectrum from the first prism or specify the size or geometry of the second.[1]

It was not until 1676, four years after Newton’s initial publication, that he performed more trials and gave people enough information to replicate them. Newton finally stated that the best prisms to use were those made in London, not Italy, as these were the clearest. Newton stated that those who failed to replicate his experiments must have been using bad prisms, but this was often seen as an excuse and Newton eventually withdrew from the debate.[1]

3.4 Huygens’ wave theory

In 1678, the Dutch natural philosopher Christiaan Huygens claimed to have disproved Newton’s theory by showing that the laws of reflection and refraction can be derived from his wave theory of light.[7]

Huygens argued that diffraction occurs because of the interference of wavefronts. When light is pushed through a small slit, waves are pushed together at different angles and this creates fringes of light and dark shadows, an interference pattern. This is how water waves behave when they pass through a small gap.

(Video) 9 07 What is Newton’s Corpuscular theory of light

Huygens believed that light waves differ from water waves in one respect: water waves are transverse, the waves move up and down like a sine wave while the water moves forward. Huygens thought that light waves were longitudinal, moving in a parallel direction to the beam.[8]

Sound is an example of a longitudinal wave because sound waves move forward by periodically displacing molecules in the air, but the molecules themselves do not move forward, they simply vibrate.

Newton's theory of Light (2)

Figure 3.2
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A longitudinal wave.

Newton's theory of Light (3)

(Video) Newton's Light Spectrum Experiment | Earth Lab

Figure 3.3
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A transverse wave.

Newton's theory of Light (4)

Figure 3.4
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The direction of oscillation and propagation of longitudinal and transverse waves.

For light to move through space as either type of wave, it must have a medium to move through. This meant that Huygens’ theory, like all theories of light before it, relied on the idea that the universe is filled with Aristotle’s fifth element, the aether.

(Video) Newton's Corpuscular Theory | Physics Animation

3.5 Bartholin’s calcite crystals

In 1669, three years before Newton first presented his particle theory of light, the Danish natural philosopher Erasmus Bartholin had begun experimenting with transparent calcite crystals, which had been discovered in Iceland. He found that when an image is placed behind a crystal it’s duplicated, with one copy appearing slightly higher than the other.[8,9]

When Bartholin rotated the crystal, he saw that one image disappeared while the other rotated with it. This led him to conclude that something in the crystal had split the beam of light into two different rays. Bartholin referred to this as “one of the greatest wonders that nature has produced”, and believed it provided evidence for Huygens’ wave theory of light.[10]

Newton's theory of Light (5)

Figure 3.5
Image credit

Double refraction within a calcite crystal.

Huygens suggested that Bartholin’s findings could be explained if the crystal contained two different materials, one that produced spherical waves and one that produced ellipsoidal waves. Huygens continued Bartholin’s experiments and found that if he placed two crystals next to each other, then the number of images varied depending on whether the crystals were placed parallel or perpendicular to each other. This was something that his wave theory of light could not explain[11] (discussed further in Chapter 5).

3.6 Newton’s Opticks

Newton did not contribute to the debate until after Hooke’s death, 32 years after his original publication. In 1704, he was elected President of the Royal Society and published Opticks, his most comprehensive theory of light. In the opening sections of the book, Newton showed how to reconstruct his prism experiments in more detail, which led to many more successful reconstructions.[1,5]

(Video) Isaac Newton Light Theory Explaination

Newton interpreted Huygens’ findings in terms of his own particle theory of light. He suggested that the experiments with the calcite crystals showed that light has ‘sides’.

Newton also used the publication of Opticks to defend his stance on diffraction. To do so, he had to appeal to wave-like properties and argued that particles of light create waves in the aether. After the publication of Opticks, Newton’s theory gained considerable popularity but some of his critics remained unconvinced.[1]

There was one way to prove which theory is correct: if light is composed of particles then it should travel faster in a denser medium, but if it’s composed of waves, then a denser medium should slow it down. This experiment would not be conducted for another 150 years, but by the end of the 19th century, both theories would be proven wrong.

FAQs

How did Newton prove his theory of light? ›

Newton's crucial experiment was to refract light onto a piece of wood, into which had been drilled a small hole. In this way, he was able to obtain a beam of light with a pure color. He was able to show that blue light, for instance, when refracted through a second prism yielded again only blue light.

Why did Newton's corpuscular theory of light fail? ›

1. Newton's corpuscular theory fails to explain simultaneous phenomenon of partial reflection and refraction on the surface of transparent medium such as glass or water. 2. The corpuscular theory fails to explain optical phenomena such as interference, diffraction, polarization etc.

Which theory of light is correct? ›

Later, in 1803, the experiment conducted by Thomas Young on the interference of light proved the Huygens wave theory of light to be correct.

What is Newton's law of light? ›

Sir Issac Newton proposed the corpuscular theory to explain the properties of light. According to this theory, light is made from small and extremely light particles called corpuscles. When these corpuscles travelling in straight line hit the retina of the eye, it produces the sensation of vision.

How many theories of light are there? ›

There are two theories of light. In the seventeenth century, two contradicting theories of the nature of light were proposed: wave theory and the corpuscular theory.

Why did Newton put 7 colors in the rainbow? ›

Newton decided to divide the rainbow into seven colors because he believed seven was a cosmically significant, even “magic” number. The musical scale has seven notes, and Newton decided to define seven distinct colors as well.

Who disprove the corpuscular theory? ›

Euler also rejected Newton's essentially corpuscular theory of the nature of light by explaining optical phenomena in terms of vibrations in a fluid ether.

Which is correct about the corpuscular theory? ›

The corpuscular theory explains that light carries energy and momentum, light travels in a straight line, Propagation of light in vacuum, Laws of reflection and refraction but it fails to explain interference, diffraction and polarization. Such brief development was done by Isaac Newton. Hence option B is correct.

What is the difference between corpuscular theory and wave theory? ›

According to Huygens wave theory the light was made up of wave not a particle. But by the prism experiment considered by Newton's corpuscular theory it is clear that light has small particles. Actually light shows both nature due to the photons light wave as well as particle nature.

What is the most accepted theory of light? ›

Light Is a Wave!

The wave theory, which maintains that light is a wave, was proposed around the same time as Newton's theory. In 1665, Italian physicist Francesco Maria Grimaldi (1618 to 1663) discovered the phenomenon of light diffraction and pointed out that it resembles the behavior of waves.

What are the three theories of light? ›

The four theories of Light
  • Newton's corpuscular theory.
  • Huygen's wave theory.
  • Maxwell's electro magnetic wave theory.
  • Planck's quantum theory.
17 Jan 2010

Who proved light is a wave? ›

In 1801 a physicist in England, Thomas Young, performed an experiment that showed that light behaves as a wave. He passed a beam of light through two thin, parallel slits.

What theory explains light as a particle? ›

Newton's corpuscular theory stated that light consisted of particles that travelled in straight lines. Huygens argued that if light were made of particles, when light beams crossed, the particles would collide and cancel each other. He proposed that light was a wave.

What are the nature of light? ›

Light is a transverse electromagnetic wave that can be seen by humans. The wave nature of light was first illustrated through experiments on diffraction and interference. Like all electromagnetic waves, light can travel through a vacuum.

Is light a wave or a particle? ›

Light can be described both as a wave and as a particle. There are two experiments in particular that have revealed the dual nature of light. When we're thinking of light as being made of of particles, these particles are called “photons”. Photons have no mass, and each one carries a specific amount of energy.

What are 4 properties of light? ›

The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum and polarization.

What are the 5 characteristics of light? ›

Photography is “writing with light.” So, let's build our conversation about lighting on five fundamental characteristics of light: Direction, Intensity, Color, Contrast, and Hardness.

What are the theories about light? ›

In optics, the corpuscular theory of light states that light is made up of small discrete particles called "corpuscles" (little particles) which travel in a straight line with a finite velocity and possess impetus. This was based on an alternate description of atomism of the time period.

Why is indigo not a color? ›

Indigo is omitted because few people can differentiate the wavelengths well enough to see it as a separate color. The six-color spectrum also fits the model of the color wheel, with red, yellow, and blue being primary colors. Orange, green, and violet are secondary colors and are spaced between the primary colors.

Is indigo a real colour? ›

Indigo is a rich color between blue and violet on the visible spectrum, it's a dark purplish blue. Dark denim is indigo as is Indigo dye. It's a cool, deep color and also a natural one. True Indigo dye is extracted from tropical plants as a fermented leaf solution and mixed with lye, pressed into cakes and powdered.

How many colours exist? ›

It has been estimated that humans can distinguish roughly 10 million different colors.

Did Newton think light was a wave? ›

In the 17th century, Isaac Newton believed light was composed of a stream of corpuscles. At that time, a few scientists, most notably Dutch physicist and astronomer Christiaan Huygens, thought light was a wave vibrating in some sort of ether.

Could Newton explain diffraction? ›

Christian Huygens

Huygens focussed on the observations that light would create diffraction and interference patterns. He proposed that light consisted of waves, which was able to explain diffraction and interference. Newton's theory was unable to do this.

Who discovered light as a particle? ›

The most prominent advocate of a particle theory of light was Isaac Newton. Newton's careful investigations into the properties of light in the 1660s led to his discovery that white light consists of a mixture of colours.

What are the postulates of Newton's corpuscular theory? ›

1. Newton proposed that a source of light emits many minute, elastic, rigid and massless particles called corpuscles. 2. These particles travel through a transparent medium at very high speed in all directions along a straight line.

What is the meaning of corpuscular theory? ›

: a theory in physics: light consists of material particles sent off in all directions from luminous bodies.

Why is light dual in nature? ›

The light's dual nature ” Light is an energy form with a dual nature. Light has both particle and wave qualities, implying that it has both particle and wave aspects. Ans. A photon is a particle with energy and movement but no mass or electrical charge.

How does Newtons concept of light differ from Huygens? ›

Newton's and Huygens' Theories of Light - Key takeaways

Isaac Newton's theory of light states that light is a straight line motion made out of small particles called corpuscles. Huygens' theory of light states that light is made out of waves.

What are the salient features of corpuscular theory of light? ›

Solution : According to corpuscular theory. <br> (i)Light is emitted as tiny, massless and perfectly elastic particles called corpuscles. <br>(ii)As corpuscles are very smal the source of light does not suffer appreciable loss of mass even if it emits light for a long time.

What is the meaning of corpuscular? ›

1 : a living cell especially : one (as a red or white blood cell or a cell in cartilage or bone) not aggregated into continuous tissues. 2 : any of various small circumscribed multicellular bodies —usually used with a qualifying term Malpighian corpuscles.

Does light have speed? ›

Light from a stationary source travels at 300,000 km/sec (186,000 miles/sec).

Why does the theory of modern physics tells us about light? ›

Explanation: According to quantum theory, both light and matter are made up of microscopic particles that have wavelike qualities. Photons are the particles that make up light, whereas electrons, protons, and neutrons are the particles that make up matter.

What does the theory of modern physics tells us about light? ›

Wave-Particle Duality of Light. Quantum theory tells us that both light and matter consists of tiny particles which have wavelike properties associated with them. Light is composed of particles called photons, and matter is composed of particles called electrons, protons, neutrons.

What did Isaac Newton discover about light? ›

He demonstrated that clear white light was composed of seven visible colors. By scientifically establishing our visible spectrum (the colors we see in a rainbow), Newton laid the path for others to experiment with color in a scientific manner.

What are the 7 properties of light? ›

There are 7 basic properties of light :
  • Reflection of light.
  • Refraction of light.
  • Diffraction of light.
  • Interference of light.
  • Polarization of light.
  • Dispersion of light.
  • Scattering of light.

How is light formed? ›

Visible light is created when electrons that are located inside atoms return to their ground state after being in an excited state. Light is radiant energy, meaning it is electromagnetic radiation that can be seen with the human eye.

What is light made of? ›

Light is made of particles called photons, bundles of the electromagnetic field that carry a specific amount of energy. With sufficiently sensitive experiments, you can count photons or even perform measurements on a single one.

Is light a matter? ›

Light exists in tiny packets called photons. Photons have no rest mass and they do not occupy any volume. So light is not matter.

Why light is a particle? ›

Light behaves mainly like a wave but it can also be considered to consist of tiny packages of energy called photons. Photons carry a fixed amount of energy but have no mass. The energy of a photon depends on its wavelength: longer wavelength photons have less energy and shorter wavelength photons have more.

What are the two theories of light? ›

In physics, there are two theories by which light can be defined: the first theory defines light as particles and the second theory as waves. When considering measurement equipment such as spectro[radio]meters, which measure light in wavelengths, the second theory is the most suitable to explain light.

How can you prove that light is a particle? ›

Light is a Particle! - YouTube

What if light was only a particle? ›

If light was only a particle and not a wave, there would be no interference effect. The result of the experiment would be like firing a hail of bullets through a double slit, j. Only two spots directly behind the slits would be hit.

Does darkness absorb light? ›

Light energy can be converted into heat energy. A black object absorbs all wavelengths of light and converts them into heat, so the object gets warm. A white object reflects all wavelengths of light, so the light is not converted into heat and the temperature of the object does not increase noticeably.

How does the light travel? ›

Light travels as waves. These are transverse waves, like the ripples in a tank of water. The direction of vibration in the waves is at 90° to the direction that the light travels. Light travels in straight lines, so if you have to represent a ray of light in a drawing, always use a ruler.

What is light summary? ›

Light is electromagnetic radiation that can be detected by the human eye. Electromagnetic radiation occurs over an extremely wide range of wavelengths, from gamma rays with wavelengths less than about 1 × 1011 metres to radio waves measured in metres.

Does light have mass? ›

Light has no mass so it also has no energy according to Einstein, but how can sunlight warm the earth without energy? Light indeed carries energy via its momentum despite having no mass.

How did Newton view about the nature of light? ›

In common with most thinkers in his day, Newton thought that light was a motion of particles (light corpuscles) in straight lines.

Does light travel in a straight line? ›

Light travels in straight lines

Once light has been produced, it will keep travelling in a straight line until it hits something else. Shadows are evidence of light travelling in straight lines. An object blocks light so that it can't reach the surface where we see the shadow.

What did Newton believe about light in the late 1600's? ›

In the 17th century, Isaac Newton believed light was composed of a stream of corpuscles. At that time, a few scientists, most notably Dutch physicist and astronomer Christiaan Huygens, thought light was a wave vibrating in some sort of ether. There was evidence for both pictures.

Who discovered the particle theory of light? ›

Einstein explained the photoelectric effect by saying that "light itself is a particle," and for this he received the Nobel Prize in Physics.

What was the first experiment to show that light is a wave? ›

The first version of the double-slit experiment was carried out in 1801 by British polymath Thomas Young, according to the American Physical Society (opens in new tab) (APS). His experiment demonstrated the interference of light waves and provided evidence that light was a wave, not a particle.

What did he prove about how we see object color? ›

Newton's Rainbow. In the 1660s, English physicist and mathematician Isaac Newton began a series of experiments with sunlight and prisms. He demonstrated that clear white light was composed of seven visible colors.

Why did Newton think light was a particle? ›

In the book, Newton argued that the geometric nature of reflection and refraction of light could only be explained if light were made of particles because waves do not tend to travel in straight lines.

What is the true nature of light? ›

Following wave theory, light can be seen as a form of energy in the electromagnetic spectrum. This spectrum encompasses energy at different wavelengths, of which only a small portion ranging from roughly 380 to 780 nm can be perceived by the human eye.

What are the three theories of light? ›

The four theories of Light
  • Newton's corpuscular theory.
  • Huygen's wave theory.
  • Maxwell's electro magnetic wave theory.
  • Planck's quantum theory.
17 Jan 2010

What is light made of? ›

Light is made of particles called photons, bundles of the electromagnetic field that carry a specific amount of energy. With sufficiently sensitive experiments, you can count photons or even perform measurements on a single one.

Is light a wave or a particle? ›

Light can be described both as a wave and as a particle. There are two experiments in particular that have revealed the dual nature of light. When we're thinking of light as being made of of particles, these particles are called “photons”. Photons have no mass, and each one carries a specific amount of energy.

What proves light is a wave? ›

Light behaves as a wave - it undergoes reflection, refraction, and diffraction just like any wave would.

Which object absorbs the most visible light? ›

This means that a black object absorbs the most visible light and converts this light energy to heat. Answer 2: Black pans will absorb the most heat energy since they reflect the least light (i.e. they absorb the most light). The more light an object absorbs, the more it can be heated.

What behavior of light is evidence for a wave model of light? ›

The Modern Theory of Light

Light is made up of waves, as evidence of refraction, reflection, diffraction, interference, and polarization all prove.

How does light affect the color of an object? ›

A light source works by emitting (or outputting) various visible wavelengths of light that are then absorbed or reflected by an object. The reflected wavelengths result in the perception of color.

What color is math blue or red? ›

In fact, the color blue is associated with math because it is a cool technical color devoid of emotion and represents the kind of technical subject that is based mostly on facts and logic.

Does everyone see colors the same? ›

Not at all - while the cones in our eyes suggest we're seeing something similar it's likely that we all see just a tiny bit differently.

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