Question 1

As the magnifying power of the compound microscope increases, the depth of focus:

Accepted Answer

As the magnifying power of the compound microscope increases, the depth of focus decreases. This means that only a small area of the specimen will be in focus at any given time. The depth of focus is inversely proportional to the magnification power of the microscope. As the magnification power increases, the depth of focus decreases.

Question 2

Which microscope has the largest potential working distance?

Accepted Answer

Stereoscopic microscopes, also known as dissecting microscopes, are designed to provide a three-dimensional view of the specimen. They have a larger working distance compared to other types of microscopes, such as compound or fluorescent microscopes, making them ideal for manipulating the specimen under observation. This feature is particularly useful for tasks that require space between the objective lens and the specimen, such as dissection or the examination of larger, bulkier samples.

Question 3

A compound microscope is equipped with two objectives lenses (10x and 45x) and has a 10x ocular lens. The highest magnification attainable with this instrument is:

Accepted Answer

To determine the highest magnification attainable, we need to multiply the magnification of the objective lens by the magnification of the ocular lens.

The highest magnification with the 10x objective and 10x ocular lens would be 10 x 10 = 100x.

The highest magnification with the 45x objective and 10x ocular lens would be 45 x 10 = 450x.

Therefore, the highest magnification attainable is 450x, which is option E.

Question 4

Which microscope is best suited to the study of birefringent minerals and fibers?

Accepted Answer

Birefringent minerals and fibers exhibit double refraction, which causes light to split into two polarized rays. A polarizing microscope is best suited for studying such materials since it uses polarized light to generate contrast and enhance the appearance of birefringent samples. The other microscopes listed are not specifically designed for observing birefringent materials.

Question 5

The microscope that provides the highest resolution and greatest depth of focus is the:

Accepted Answer

SEM (Scanning Electron Microscope) is the most suitable option for providing the highest resolution and greatest depth of focus. SEM uses a focused beam of electrons to produce extremely high-resolution images of the surface of a sample. It can also generate 3D images with great depth of field.

Question 6

When using a compound microscope, the areas above and below the depth of focus are best viewed by adjusting the:

Accepted Answer

The fine or coarse adjustment knobs on a microscope are used to move the stage up or down, thereby bringing different planes of the specimen into focus. This is essential for viewing areas above and below the depth of focus clearly.

Question 7

A parfocal microscope:

Accepted Answer

A parfocal microscope is a microscope that maintains focus when magnification is changed. This means that the specimen can be focused at one magnification and then switched to a higher magnification without having to adjust the focus significantly. This makes it easier to view and study the specimen.

Question 8

Which microscope provides a right-side-up image?

Accepted Answer

The stereoscopic microscope provides a right-side-up image. This is because it uses two separate optical pathways that enable the viewer to see a three-dimensional image with correct orientation. Unlike the compound microscope, which produces an inverted image, or the polarizing microscope, which can produce a range of images depending on the orientation of the polarizer and analyzer, the stereoscopic microscope produces a naturally oriented image.

Question 9

The polarizer and analyzer in a polarizing microscope are normally set:

Accepted Answer

To create a polarized light, the analyzer and polarizer should be perpendicular to each other. This is because only light waves oscillating in a single plane will be allowed to pass through the analyzer, which is perpendicular to the polarizer. Hence, this state generates maximum contrast between different parts of the sample, allowing for the best viewing.

Question 10

A comparison microscope designed to examine bullets and fibers is equipped with:

Accepted Answer

A comparison microscope is usually equipped with both vertical and transmitted illumination for examining bullets and fibers. Vertical illumination is used to observe the surface characteristics and scarring patterns of bullets, while transmitted illumination is used to view the internal structure of fibers. The oblique illumination is not typically used in this type of forensic analysis.

Question 11

The condenser of a compound microscope is located:

Accepted Answer

The condenser of a compound microscope is located beneath the stage. It helps to focus the light onto the specimen, making it more visible under the microscope.

Question 12

The image produced by an SEM is initially displayed on:

Accepted Answer

The image produced by an SEM (Scanning Electron Microscope) is initially displayed on a cathode ray tube, which allows for real-time imaging and manipulation. X-ray film, photographic paper, and x-ray analyzers are not used for the initial display of SEM images. While photographic paper can be used to print a hard copy of the image, it is not the primary display medium.

Question 13

Which microscope plots an absorption spectrum of the item under examination?

Accepted Answer

A microspectrophotometer is specifically designed to plot an absorption spectrum of an item under examination, while the other types of microscopes listed do not have this capability.

Question 14

________ are used to focus the SEM (scanning electron microscope).

Accepted Answer

Magnets are used in a scanning electron microscope (SEM) to focus the electron beam. Unlike light microscopes that use glass lenses to focus light, SEMs use electromagnetic lenses to focus electrons.

Question 15

In the design of a polarizing microscope, the polarizer is placed between the:

Accepted Answer

In a polarizing microscope, the polarizer is placed between the light source and the sample stage. This is because the polarizer is responsible for polarizing the light before it enters the sample, which then interacts with the specimen and produces birefringence or double refraction. The analyzer is then placed between the sample and the eyepiece to allow only a certain plane of polarized light to pass through and be viewed by the observer.

Question 16

A microscope with which light source, when linked to a spectrophotometer, will provide a "fingerprint" spectrum of the object being viewed?

Accepted Answer

Infrared (IR) light, when used with a spectrophotometer, can provide a "fingerprint" spectrum because different molecular bonds absorb specific IR wavelengths, allowing for the identification of substances based on their unique absorption patterns.

Question 17

An object with the letter "L" is viewed under low power of a compound microscope. The image would appear as:

Accepted Answer

The answer of An object with the letter "L" is...

Question 18

As the magnification of the compound microscope is increased, the field of view:

Accepted Answer

As the magnification increases, the field of view decreases. This means that at higher magnifications, you see a smaller area of the specimen being observed.

Question 19

The resolving power of a lens with a numerical aperture (N.A.) of 1.3 is ________ a lens with an N.A. of 0.65.

Accepted Answer

The resolving power of a lens is directly proportional to its numerical aperture. Therefore, a lens with an N.A. of 1.3 will have a higher resolving power compared to a lens with an N.A. of 0.65.

Question 20

In order to examine an opaque object with a compound microscope, one must:

Accepted Answer

For examining opaque objects with a compound microscope, reflected illumination (also known as incident light) is used because the light reflects off the surface of the object into the microscope, allowing for visualization. Transmitted illumination (lighting the object from beneath) is not effective for opaque objects as they do not allow light to pass through them for viewing.

Quiz 7: Crime-Scene Reconstruction