/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 68 A thick layer of oil is floating... [FREE SOLUTION] | 91Ó°ÊÓ

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A thick layer of oil is floating on the surface of water in a tank. A beam of light traveling in the oil is incident on the water interface at an angle of \(30.0^{\circ}\) from the normal. The refracted beam travels in the water at an angle of \(45.0^{\circ}\) from the normal. What is the refractive index of the oil?

Short Answer

Expert verified
The refractive index of the oil is 1.88.

Step by step solution

01

Understand the Snell's Law

Snell's Law relates the angles of incidence and refraction to the refractive indices of the media involved. The law is given by the equation: \[ n_1 \sin(\theta_1) = n_2 \sin(\theta_2) \]where \( n_1 \) and \( n_2 \) are the refractive indices of the media, and \( \theta_1 \) and \( \theta_2 \) are the angles of incidence and refraction, respectively.
02

Assign Known Values

In this problem: - The angle of incidence \( \theta_1 = 30.0^{\circ} \) in oil.- The angle of refraction \( \theta_2 = 45.0^{\circ} \) in water.- The refractive index of water \( n_2 = 1.33 \).We need to find the refractive index \( n_1 \) of the oil.
03

Apply Snell's Law

We input the known values into Snell's Law equation:\[ n_1 \sin(30.0^{\circ}) = 1.33 \sin(45.0^{\circ}) \]
04

Solve for the Refractive Index of Oil

Now solve the equation for \( n_1 \):\[ n_1 = \frac{1.33 \sin(45.0^{\circ})}{\sin(30.0^{\circ})} \]Calculate the sine values:- \( \sin(30.0^{\circ}) = 0.5 \)- \( \sin(45.0^{\circ}) = \frac{\sqrt{2}}{2} \approx 0.707 \)Substitute these into the equation:\[ n_1 = \frac{1.33 \times 0.707}{0.5} = 1.88 \]
05

Verify Solution

The calculation gives \( n_1 = 1.88 \). Verify by ensuring all steps are followed correctly and calculations checked for errors in trigonometric values and division.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Refractive Index
The refractive index, often denoted as "n," is a fundamental concept in optics, reflecting how light propagates through different media. It is defined as the ratio of the speed of light in a vacuum to the speed of light in the given medium.
The formula can be expressed as:
  • \( n = \frac{c}{v} \)
where \( c \) is the speed of light in vacuum, and \( v \) is the speed of light in the medium.
A higher refractive index indicates that light travels slower in the medium, leading to greater bending of the light as it passes from one medium to another.
It explains phenomena like bending of light when entering materials with different optical densities, like glasses, water, or oils. Understanding refractive indices is crucial for designing lenses and other optical devices.
Angle of Incidence
The angle of incidence is the angle between the incoming light ray and the perpendicular (normal) line to the surface at the point of contact. This angle is pivotal in determining how the light will refract when transitioning from one medium to another.
In our initial problem, the angle of incidence in the oil was given as \( 30.0^{\circ} \). This angle is essential because it interacts with the medium's refractive index to determine the outcome of light bending. According to Snell's Law, the angle of incidence, combined with the refractive indices, helps calculate the angle of refraction in a second medium.
Ultimately, the concept of the angle of incidence is vital in predicting the path of light, designing optical equipment, and understanding natural phenomena.
Angle of Refraction
The angle of refraction is the angle formed between the refracted light ray and the normal to the surface after transitioning into a new medium. It is a crucial concept, helping us understand how dramatically light bends once it enters a medium with a different refractive index.
From the original scenario, the light traveled into water at an angle of refraction of \( 45.0^{\circ} \). The angle of refraction is determined by Snell's Law, which considers both the refractive indices of the two media and the angle of incidence.
  • Snell's Law: \( n_1 \sin(\theta_1) = n_2 \sin(\theta_2) \)
This law allows us to compute how much the light will bend or refract when entering a new medium. Understanding it is crucial for applications like fiber optics, lenses, and for gaining insights into natural optical illusions.
Trigonometry in Physics
Trigonometry plays a significant role in physics, particularly when dealing with light and optics. It is instrumental in calculations involving angles and distances, such as those encountered in Snell's Law.

Role of Trigonometry in Optics:

  • Trigonometric functions, like sine, cosine, and tangent, help describe angles of incidence and refraction.
  • In the given exercise, calculating the sine of the given angles was necessary to solve for the refractive index of the oil.
  • These functions allow accurate computation of an angle's effect on the direction of light travel.
Understanding how trigonometry applies to light's behavior is essential for solving physics problems, crafting precise lenses, and improving technologies such as cameras and telescopes.

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Most popular questions from this chapter

(a) How much time does it take light to travel from the moon to the earth, a distance of \(384,000 \mathrm{~km} ?\) (b) Light from the star Sirius takes 8.61 years to reach the earth. What is the distance to Sirius in kilometers?

The vitreous humor, a transparent, gelatinous fluid that fills most of the eyeball, has an index of refraction of \(1.34 .\) Visible light ranges in wavelength from \(400 \mathrm{nm}\) (violet) to \(700 \mathrm{nm}\) (red), as measured in air. This light travels through the vitreous humor and strikes the rods and cones at the surface of the retina. What are the ranges of (a) the wavelength, (b) the frequency, and (c) the speed of the light just as it approaches the retina within the vitreous humor?

You want to support a sheet of fireproof paper horizontally, using only a vertical upward beam of light spread uniformly over the sheet. There is no other light on this paper. The sheet measures \(22.0 \mathrm{~cm}\) by \(28.0 \mathrm{~cm}\) and has a mass of \(1.50 \mathrm{~g}\). (a) If the paper is black and hence absorbs all the light that hits it, what must be the intensity of the light beam? (b) For the light in part (a), what are the maximum values of its electric and magnetic fields? (c) If the paper is white and hence reflects all the light that hits it, what intensity of light beam is needed to support it? (d) To see if it is physically reasonable to expect to support a sheet of paper this way, calculate the intensity in a typical \(0.500 \mathrm{~mW}\) laser beam that is \(1.00 \mathrm{~mm}\) in diameter and compare this value with your answer in part (a).

Write the wave equation for the electric field of an electromagnetic wave that is traveling in the \(+x\) direction with a wavelength of \(2.0 \mathrm{~m}\) and an amplitude of \(100 \mathrm{~N} / \mathrm{C}\). Give the wave equation in terms of its angular frequency and wave number.

Laser surgery. Very short pulses of high-intensity laser beams are used to repair detached portions of the retina of the eye. The brief pulses of energy absorbed by the retina weld the detached portion back into place. In one such procedure, a laser beam has a wavelength of \(810 \mathrm{nm}\) and delivers \(250 \mathrm{~mW}\) of power spread over a circular spot \(510 \mu \mathrm{m}\) in diameter. The vitreous humor (the transparent fluid that fills most of the eye) has an index of refraction of \(1.34 .\) (a) If the laser pulses are each \(1.50 \mathrm{~ms}\) long, how much energy is delivered to the retina with each pulse? (b) What average pressure does the pulse of the laser beam exert on the retina as it is fully absorbed by the circular spot? (c) What are the wavelength and frequency of the laser light inside the vitreous humor of the eye? (d) What are the maximum values of the electric and magnetic fields in the laser beam?

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