Biology - Microscope

What is a microscope?

A scientific instrument that magnifies and resolves details of small objects, making them appear larger and clearer than with the unaided eye.

What are the two main types of microscopes?

Light microscope and Electron microscope.

What does a Light Microscope use to magnify specimens?

Two or more lenses and visible light.

In a Light Microscope, where does light pass after the specimen before reaching the viewer?

Through the objective lens and eyepiece to the eye.

What is the function of the Stage in a Light Microscope?

A platform that holds the slide for observation.

What is the purpose of the Eyepiece Lens?

The part you look through to view the magnified image.

What is the Arm of a microscope used for?

Supports and connects the eyepiece to the base; also a handle for carrying.

What is a Slide?

A thin piece of glass that holds the specimen.

What is the Focus Wheel used for?

To bring the object into or out of focus.

What is the Lamp's role in a Light Microscope?

Provides light to illuminate the specimen (sometimes used with a mirror).

What is the Base of a microscope used for?

Supports the microscope.

What is Magnification?

How much larger an image appears compared to the actual size.

What is the Magnification formula?

Magnification = Image size ÷ Actual size.

If a cell is 10 μm in real size and appears 100 μm on the image, what is the magnification?

×10.

What is the Limit of resolution for a Light Microscope?

Half the wavelength of the light used (about 200 nm for visible light).

Why can't ribosomes be seen with a light microscope?

Because they are about 25 nm in size, smaller than the light microscope’s resolution, and do not interfere with light waves.

What is an Electron Microscope?

A microscope that uses a beam of accelerated electrons for illumination, offering very high resolution and nanometre-scale magnification; image is captured on a phosphorescent screen and is black and white.

What is the color of images produced by Electron Microscopes?

Black and white.

What are TEM and SEM in electron microscopy?

Two types: Transmission Electron Microscope (TEM) images interiors; Scanning Electron Microscope (SEM) images surfaces.

What does TEM image?

The interior of cells and their organelles.

What does SEM image?

The surfaces of cells and whole organisms.

Which type of microscope provides higher resolution, light or electron microscopes?

Electron microscopes provide much higher resolution than light microscopes.

What is the role of