Physics Exam 2 (Multiple Choice)

The "color temperature" of a xenon light bulb is given as 6000 K; for a compact fluorescent bulb (cfl), it is 5000 K; and for an incandescent bulb it is around 3000 K. At what wavelength of light does the radiation peak occur for each of these approximate blackbodies?

about 480 nm xenon, about 580 nm cfl, about 970 nm incandescent

One type of objective lens with a high degree of chromatic and spherical aberration correction is known as an ______________ objective.

apochromatic

Dr. Kaech-Petrie obtained her Ph.D. in __?

biochemistry

The Sun is so far from Earth that rays of sunlight are effectively parallel when they reach Earth's surface. Sunlight reflected from a mirror can be focused onto a pot of water, raising its temperature enough to pasteurize water or cook food. What kind of spherical mirror could be used for this purpose?

concave mirror

Dealing with the blurring of dense labeling in thicker pieces of tissue was made easier with the invention of the laser scanning ____ microscope in the 1970s.

confocal

Ernst Abbe developed theories in optics demonstrating that _____________ is the determining factor for resolution and contrast.

diffraction

Look up the temperature of the sun. To which artificial light source's color temperature is it most similar?

it is similar to the xenon bulb (5778 K sun, 6000 K xenon bulb)

The main change that has taken place in microscopy over the last couple of decades is....

it's done digitally

Light rays from a distant object are essentially parallel. That's why to focus a digital camera on a distant object, the lens is adjusted so that the distance from the lens to the CCD array or other electronic image sensor (which records the image) is equal to the focal length f. To focus on a nearby object, the lens must be positioned so that the distance from the lens to the image sensor is:

more than f (as the object approaches the lens, the object distance decreases, and consequently the image distance increases since the focal length does not change. The lens must be then positioned farther away from the sensor than the focal length f)

To increase the magnitude of the magnification of a compound microscope, you can:

more than one of the above; The magnification of a microscope is given by m=−L(Lnp)fofe. So to increase the magnitude of the magnification you can increase one or both quantities in the numerator, like L, which is related to the distance between the eyepiece and the objective. You could also use a shorter focal length eyepiece, which would decrease the denominator, and so also increase the magnification of the microscope.

Another method of optical sectioning is ____ ____ or two photon microscopy.

multi photon

The technique of eliminating out-of-focus light from the focal plane is called?

optical sectioning

A major breakthrough in microscopy during the first part of the last century was _______ ____________ microscopy.

phase contrast

One of the more robust technologies for passing the diffraction limit is ____________ ______________ super resolution microscopy.

structured illumination

The diffraction volume of a single fluorescent molecule is ____ times as high (in the axial direction) as its width of 1/3 of a micrometer.

two

Unfortunately, as reported by The Oregonian newspaper on January 21, 2015 in the article "Halogen lights burn about 10 Silverton Hospital patients," a number of patients who had been in one of several operating rooms sustained skin burns. The cause was later discovered to be the halogen lamps, which had been replaced but without their accompanying filters. Based on the information in this section, which of the statements below apply to this situation?

1) Halogen bulbs will emit more UV than incandescent bulbs since their operating temperature is higher 2) Since UV radiation is known to cause skin burns, the filters were likely blocking UV light

What types of microscopes does Dr. Kaech-Petrie mention overseeing in her current position?

1) basic fluorescence microscope 2) two-photon microscope 3) super-resolution microscope

According to Dr. Kaech-Petrie, what are some of the advancements an automated microscope has over a manual microscope?

1) change light path 2) automatic start/stop of illumination 3) movement of the sample in 3D with respect to the objective

What common aberrations in microscopy are discussed by Dr. Kaech-Petrie?

1) curved images 2) chromatic aberration 3) spherical aberration

Another approach to passing the diffraction limit involves:

1) recording fluorescence from a single molecule 2) taking up to tens of thousands of images 3) making approximations of where the single molecules were situated

Some techniques used at the turn of the century are still used today for diagnostics. Which of these did Dr. Kaech-Petrie mention?

1) stains 2) dyes

What characterizes multi-photon microscopy?

1) temporally and spatially lower wavelength photons 2) excitation only in the focal plane of the objective 3) excitation deeper in the tissue 4) picking up scattered photons from the diffraction spot

Greater magnification is gained over a simple magnifying glass:

1) with a compound microscope 2) by adding more lenses

For imaging with light, the diffraction limit dictates that two structures must be separated by at least _____ nm to be resolvable.

300

A shiny spoon is not so different in shape than a spherical mirror. Your reflection from the concave side of the spoon, when held at arm's length, is upside down and appears to float in front of the spoon. When you hold the spoon about 6 cm from your eye you see only a blur reflected in the spoon, but when you hold it about 4 cm from your eye, your reflection is right side up and appears to be behind the spoon. The approximate focal length of the spoon is:

6 cm (The spoon is acting here as a concave mirror. At the focal point, no image is formed because light rays from any point on your face are reflected parallel to each other.)