The objective lens and the eyepiece of a microscope have focal lengths of 4.0 mm and 25 mm, respectively.
The objective produces a real image 30 times the size of the object, with the final image viewed at infinity. The near point of the microscope user is at 25 cm. What is the magnitude of the overall magnification of the microscope?
A) 250
B) 300
C) 350
D) 400
E) 450
Question 2
A circular coil of copper wire is lying flat on a horizontal table. A bar magnet is held above the center of the coil with its south pole downward. The magnet is released from rest and falls toward the coil.
As viewed from above, what is the direction of the current induced in the coil as the magnet approaches the coil? A) counterclockwise
B) clockwise
C) No current is induced in the coil.
D) An emf but no current is induced in the coil.
Electron Microscope
Insects Under the Electron Microscope
An ant under an electron microscope
Scorpions, Spiders and Sharks: Electron-Microscope Images
Lens
Using and Cleaning the Microscope