Physics Chapter 5 Quiz

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Questions and Answers

How long does it take for the sun to shift by 1° when viewed from the earth?

2 minutes

4 minutes (correct)

6 minutes

1 minute

When a lifeguard wants to reach a drowning child in the shortest possible time, which law must be satisfied?

Law of Conservation of Energy

Newton's Law of Motion

Law of Universal Gravitation

Snell's Law (correct)

What phenomenon occurs when light travels from an optically denser medium to a rarer medium?

Partial reflection and refraction (correct)

Reflection and absorption

Refraction and diffusion

Total internal reflection

In the context of Snell's law, when does the time taken to reach a target become a minimum?

When the ratio of velocities satisfies the equation $\frac{sin(i)}{sin(r)} = \frac{v_1}{v_2}$ Signup and view all the answers

What is the term used when light is reflected back into the same medium at an interface?

Total internal reflection Signup and view all the answers

What can be inferred if the lifeguard's running speed on ground is greater than his swimming speed?

He should minimize his time in the water Signup and view all the answers

In Snell's law, what does the variable 'n' represent?

The refractive index of a medium Signup and view all the answers

What is the object distance for the second lens based on the image formed by the first lens?

10 cm Signup and view all the answers

What is the result of the rays appearing to come from the image formed by the first lens for the second lens?

The image is virtual. Signup and view all the answers

What is the value of the image distance v3 formed by the third lens?

30 cm Signup and view all the answers

According to the equations given, what does the equation r1 + r2 = A represent in the context of a prism?

The sum of angles within the prism. Signup and view all the answers

What is defined as the angle between the emergent ray and the direction of the incident ray in the context of light passing through a prism?

Angle of deviation Signup and view all the answers

What happens when a ray of light transitions from a denser medium to a rarer medium?

It bends away from the normal. Signup and view all the answers

What occurs when the angle of incidence exceeds the critical angle?

Total internal reflection occurs. Signup and view all the answers

Which statement about total internal reflection is true?

No transmission of light occurs. Signup and view all the answers

What is the relationship between the angle of incidence and the angle of refraction as the angle of incidence increases, up to the critical angle?

The angle of refraction increases. Signup and view all the answers

What does the term 'critical angle' refer to?

The angle of incidence resulting in total internal reflection. Signup and view all the answers

How does the intensity of the reflected ray compare to the incident ray in normal reflection?

The reflected ray has less intensity. Signup and view all the answers

Which of the following is true regarding the angle of refraction when the light is bent away from the normal?

The angle of refraction can be greater than the angle of incidence. Signup and view all the answers

What defines the behavior of light at the interface between two media?

Refraction and reflection occur due to differing refractive indices. Signup and view all the answers

In the context of light physics, what does partial transmission refer to?

Some light is refracted while some is reflected. Signup and view all the answers

What happens to the wavelength region of radiation emitted by a body as its temperature increases?

It shifts towards the visible region. Signup and view all the answers

What is the SI unit for luminous intensity?

Candela Signup and view all the answers

What is the unit of illuminance?

lm/m2 Signup and view all the answers

For a source emitting one candela of luminous intensity into one steradian, how much luminous flux is emitted?

One lumen Signup and view all the answers

How is illuminance E related to luminous intensity I?

E = I/r^2 Signup and view all the answers

What is the primary focus of photometry?

Measurement of light as perceived by the human eye. Signup and view all the answers

At approximately what temperature does the sun emit radiation that peaks at around 550 nm?

5500 K Signup and view all the answers

What characterizes the brightness of emitting or reflecting flat surfaces?

Luminance Signup and view all the answers

What is the typical brightness of a good LCD computer monitor?

250 nits Signup and view all the answers

What is the relationship between wavelength and absolute temperature for radiation emitted by a body?

Wavelength is inversely proportional to temperature. Signup and view all the answers

Which parameter can be measured directly in photometry?

Illuminance Signup and view all the answers

In the equation n1 sin i = n2 sin r, what does 'i' represent?

Exterior angle Signup and view all the answers

What does the variable R represent in the context of curved spherical surfaces?

Radius of curvature Signup and view all the answers

What is the radiant intensity in the direction of one candela of luminous intensity?

1 watt per steradian Signup and view all the answers

What is the refractive index of glass typically used in optical calculations?

1.5 Signup and view all the answers

What type of radiation is predominantly emitted by a tungsten filament lamp at 2850 K?

Infrared radiation Signup and view all the answers

Which of the following statements about luminous flux is true?

It is the flow of light from a source. Signup and view all the answers

Using the equation v = (n2/n1) * R in optical scenarios, what does 'v' indicate?

Image distance Signup and view all the answers

What is the distance of the light source from the spherical glass surface in the example provided?

100 cm Signup and view all the answers

According to Snell's law for small angles, how is the relation simplified?

n1 i = n2 r Signup and view all the answers

Study Notes

Ray Optics and Optical Instruments

Introduction: Nature allows humans to perceive and interpret the world through light, electromagnetic radiation within a specific wavelength spectrum (400 nm to 750 nm). Light travels at an enormous speed (c = 3 × 10⁸ m/s in a vacuum), in a straight line. The wavelength of light is small compared to most objects, allowing for straight-line approximations.
Particle model of Light: Newton's corpuscular model proposed light as massless elastic particles. Newton's model explained reflection, but failed in refraction. The speed of light in a medium is less than in a vacuum, according to later discoveries. This implies that the particle speed is actually dependent on the material, not simply the particle itself.
Reflection by Spherical Mirrors:
- Laws of Reflection: The angle of incidence equals the angle of reflection, and the incident ray, reflected ray and the normal lie in the same plane.
- Sign Convention: Distances measured towards incident light are considered positive, and those in the opposite direction are negative. Heights measured upwards are positive, while those below the principal axis are negative.
Focal Length of Spherical Mirrors: A parallel beam of light converges at the principal focus (F) of a concave mirror and appears to diverge from the principal focus of a convex mirror. The distance between the focus and the pole (P) is the focal length (f). The focal length equals half the radius of curvature (R) of the mirror.
Mirror Equation and Magnification
- The mirror equation relates object distance (u), image distance (v), and focal length (f): 1/u + 1/v = 1/f
- The linear magnification (m) relates the height of the image (h') to the height of the object (h): m = h'/h = -v/u, showing the relationship between object and image size.
Refraction of Light by Spherical Surfaces:
- Snell's Law describes the relationship between the angles of incidence (i) and refraction (r) at the interface of two media: n₁ sin i = n₂ sin r, where n₁ and n₂ are the refractive indices of the two media. Refraction causes a bending of light as it passes from one medium to another.
Refraction by a Lens:
- The lens maker's formula describes the focal length of a lens in terms of its refractive index (n) and the radii of curvature of its surfaces (R₁ and R₂): 1/f = (n-1)(1/R₁ - 1/R₂)
- The lens formula relates object distance (u), image distance (v), and focal length (f) for a thin lens: 1/u + 1/v = 1/f
Total Internal Reflection:
- Total internal reflection (TIR) is when light incident from a denser medium on a less dense medium experiences complete reflection at the interface, when the angle of incidence exceeds a critical angle.
- This phenomenon is important for optical fibres and other applications.
Optical Instruments:
- Eye lens: The eye can change its focal length through ciliary muscles, allowing for different focus distances (accommodation).
- Magnifying glass (simple microscope): A converging lens used to magnify an object by having the object placed within its focal length.
- Compound microscope: Uses multiple lenses (objective and eyepiece) to create a highly magnified image.
- Telescope: A telescope uses a large objective lens or mirror to collect and focus light from distant objects. The eyepiece serves to magnify the image.
- Prisms: Prisms can split light into its component colours (dispersion) due to wavelength-dependent refractive indices.
Dispersion:
The splitting of white light into its component colours by a prism, is due to the difference in refractive indices for different wavelengths. The amount of deviation varies with the wavelength (colors).
Scattering of Light:
- Scattering of light by air particles, such as in Rayleigh scattering, is greater for shorter wavelengths, making the sky appear blue. At sunrise and sunset, light travels through more atmosphere, with the shorter wavelengths being scattered away, and the longer wavelengths (red) reaching the observer.
Rainbow:
Rainbows are a result of dispersion, reflection, and refraction in spherical water droplets. Light is refracted, internally reflected, and refracted again forming a spectrum of colors visible to a person positioned with the back toward the sun.

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Description

Test your understanding of key physics concepts related to light, refraction, and motion. This quiz covers topics such as Snell's law, lifeguard scenarios, and the behavior of light in different media. Challenge yourself and see how well you grasp these fundamental principles!