/*! 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 7 \(\cdot\) A certain digital came... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

\(\cdot\) A certain digital camera having a lens with focal length 7.50 \(\mathrm{cm}\) focuses on an object 1.85 m tall that is 4.25 \(\mathrm{m}\) from the lens. (a) How far must the lens be from the sensor array? (b) How tall is the image on the sensor array? Is it erect or inverted? Real or virtual? (c) A SLR digital camera often has pixels measuring 8.0\(\mu \mathrm{m} \times 8.0 \mu \mathrm{m} .\) How many such pixels does the height of this image cover?

Short Answer

Expert verified
(a) Lens should be 7.67 cm from the sensor. (b) Image is -3.34 cm: inverted, real. (c) Image height covers 4175 pixels.

Step by step solution

01

Convert Units for the Object Distance

We're given the object distance as 4.25 meters but need it in centimeters to match the focal length units. Thus, convert: \( 4.25 \text{ m} = 425 \text{ cm} \).
02

Use Lens Formula to Find Image Distance

The lens formula is \( \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \) where \( f \) is the focal length, \( v \) is the image distance, and \( u \) is the object distance. Substituting the known values: \( \frac{1}{7.5} = \frac{1}{v} + \frac{1}{425} \). Solve for \( v \).
03

Calculate Image Distance

Simplify and solve the lens equation: \[ \frac{1}{v} = \frac{1}{7.5} - \frac{1}{425} \] Compute to find \( v \). The result is \( v \approx 7.67 \text{ cm} \).
04

Determine Image Height Using Magnification

The magnification \( m \) is given by \( \frac{h'}{h} = -\frac{v}{u} \) where \( h' \) is the image height and \( h \) is the object height. Convert object height to centimeters: \( 1.85 \text{ m} = 185 \text{ cm} \). Substitute the known values to find \( h' \): \( h' = -\frac{7.67}{425} \times 185 \).
05

Calculate Image Height

Compute the value of \( h' \): The height of the image is \( h' \approx -3.34 \text{ cm} \). The minus sign indicates the image is inverted.
06

Determine Image Characteristics

Since \( v \) is positive, the image is real. The magnification being negative confirms that the image is inverted.
07

Calculate Number of Pixels Image Height Covers

Convert image height from centimeters to micrometers: \( 3.34 \text{ cm} = 33400 \mu\mathrm{m} \). Since each pixel is \( 8.0 \text{ µm} \), the number of pixels is \( \frac{33400}{8} = 4175 \).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

lens formula
In the study of optics, the lens formula is an essential tool, especially when working with lenses like those in digital cameras. The formula is given by:\[\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\]where:
  • \( f \) is the focal length of the lens,
  • \( v \) is the image distance from the lens,
  • \( u \) is the object distance from the lens.
This equation relates the distances to the focal point of the lens, allowing us to determine the position of the image formed by a lens when we know the object distance and the focal length.By rearranging the equation, one can solve for any unknown distance, be it the image distance \( v \) or the object distance \( u \), using known values. The lens formula is practical in designing and using lens systems in various optical gadgets, impacting how images are captured and processed.
image distance
Image distance is a key metric in optics and understanding it is pivotal when working with lenses. It represents the distance from the lens to the image along the principal axis.
In practical applications like the digital cameras, knowing the image distance helps to focus the camera properly and to ascertain where the image sensor should be placed to capture a clear image.
When using the given lens formula, once you plug in the focal length and the object distance, you can solve for the image distance \( v \). If \( v \) comes out positive, like in this exercise, it signifies a real image is formed, this happens on the opposite side of the light source where traditionally the camera sensor is placed.
Real images are generally inverted, meaning they need further processing or adjustment to appear correctly oriented when viewed.
magnification
Magnification is vital in optics because it tells us how much larger or smaller the image appears compared to the object. In mathematical terms, magnification \( m \) is given by:\[m = \frac{h'}{h} = -\frac{v}{u}\]Here,
  • \( h' \) is the image height,
  • \( h \) is the object height,
  • \( v \) is the image distance,
  • \( u \) is the object distance.
The negative sign indicates that the image is inverted when the lens type creates a real image. With digital cameras, knowing the magnification can help determine how accurately the camera reproduces the likeness of an object.
In calculation, once you determine both the image distance and object distance, finding the magnification becomes just a matter of applying the equation. Photographers and optics professionals use magnification to plan their shots and settings, thus enabling them to predict the scale and orientation of an image.
digital cameras
Digital cameras have revolutionized the way we capture and store images. These cameras use lenses just like traditional film cameras, but instead of film, they have sensor arrays that capture light and convert it into a digital signal.
The lenses in digital cameras work similarly to any other lens, adhering to the same principles of the lens formula to focus light beams onto the sensor.
One distinguishing feature is that digital cameras offer flexibility in processing images, such as resizing, adjusting brightness, or even changing orientation after the image is captured.
With regard to pixel resolution, a digital camera's sensor is usually made up of a grid of small pixels — each pixel corresponding to a certain area of the image. For instance, in this exercise, knowing the image height in micrometers and dividing by the pixel size helps determine the number of pixels the image height covers. This capability defines the clarity and detail provided by the camera, affecting everything from the number of pixels to image processing directly.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A telescope is constructed from two lenses with focal lengths of 95.0 \(\mathrm{cm}\) and \(15.0 \mathrm{cm},\) the 95.0 -cm lens being used as the objective. Both the object being viewed and the final image are at infinity. (a) Find the angular magnification of the telescope. (b) Find the height of the image formed by the objective of a building 60.0 \(\mathrm{m}\) tall and 3.00 \(\mathrm{km}\) away. (c) What is the angular size of the final image as viewed by an eye very close to the eyepiece?

\(\bullet\) It's all done with mirrors. A photographer standing 0.750 \(\mathrm{m}\) in front of a plane mirror is taking a photograph of her image in the mirror, using a digital camera having a lens with a focal length of 19.5 \(\mathrm{mm}\) (a) How far is the lens from the light sensors of the camera? (b) If the camera is 8.0 \(\mathrm{cm}\) high, how high is its image on the sensors?

A student's far point is at \(17.0 \mathrm{cm},\) and she needs glasses to view her computer screen comfortably at a distance of 45.0 \(\mathrm{cm} .\) What should be the power of the lenses for her glasses?

Crystalline lens of the eye. The crystalline lens of the eye is double convex and has a typical index of refraction of \(1.43 .\) At minimum power, the front surface has a radius of 10.0 \(\mathrm{mm}\) and the back surface has a radius of 6.0 \(\mathrm{mm}\) ; at maximum power, these radii are 6.0 \(\mathrm{mm}\) and 5.5 \(\mathrm{mm}\) , respectively (although the values do vary from person to person). (a) Find the maximum and minimum power (in diopters) of the crystalline lens if it were in air. (b) What is the range of focal lengths the eye can achieve? (c) At minimum power, where does it focus the image of a very distant object? (d) At maximum power, where does it focus the image of an object at the near point of 25 \(\mathrm{cm} ?\)

\(\cdot\) You want to view an insect 2.00 \(\mathrm{mm}\) in length through a magnifier. If the insect is to be at the focal point of the magnifier, what focal length will give the image of the insect an angular size of 0.025 radian?

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.