Trace how a device collects, redirects and focuses light. Connect each component with a job.
Select a page to enlarge it. The PDF contains the complete set.
A microscope reveals small nearby structures; a telescope gathers light from distant objects. Magnification alone is not enough: a useful device must also gather light and resolve detail. Increasing magnification cannot recover detail that never reached the device.
A refracting telescope uses an objective lens to form an image. A reflecting telescope uses a primary curved mirror. Other components direct the light to an eyepiece or detector. Real instruments have varied designs, so one two-element sketch is a simplified example.
A compound light microscope uses an objective and an eyepiece. The objective forms a magnified intermediate image, which the eyepiece magnifies for viewing. Many binoculars combine two telescope systems with prisms that fold the path and orient the image.
A camera lens forms a real image on film or an electronic sensor. An aperture controls incoming light. A pinhole camera can form an inverted image without a lens by limiting which straight rays reach the screen. A projection is different from looking toward a source through a hole.
Compare microscopes, telescopes, binoculars and cameras using their light paths.
Physics Girl · Behind the scenes
Identify the job of a lens in a large optical system. Why is a useful instrument about more than magnification?
Move the optical components and follow the resulting light paths. The scene is ready to explore below.
Drag a lens along the optical axis. Follow the rays and their backward extensions. Reset to restore the original arrangement.
Which lens forms the intermediate image, and which helps you view it?
A microscope has 10× eyepiece and 20× objective. State the total magnification and explain your reasoning.
Multiply, rather than add, the factors.
10 × 20 = 200×.
Does a pinhole camera require a lens? State yes or no and explain your reasoning.
Selected straight ray paths can form an image.
A pinhole limits paths and can form an inverted image without a lens.
Why does a microscope need both illumination and a useful objective?
The specimen must send light into the objective. The objective must resolve useful detail; an eyepiece can enlarge that image but cannot invent missing detail.
Reflecting telescopes collect light with a mirror. Instruments can also use detectors rather than a human eyepiece.
Commit to an answer, then use the feedback to check your reasoning.
