See the invisible

The idea

A microscope magnifies tiny objects so they become visible; ordinary microscopes magnify about 100 to 400 times, while an electron microscope magnifies about 10,00,000 times and reveals subcellular structures.

How small can your eyes see?

The human eye can only see things above a certain size. A lens that is thick in the middle and thin at the edge makes small things look bigger.

A thin onion peel is a few cells thick. What will you see with your eyes alone?

• Every cell, clearly
• A thin, smooth skin
• Nothing at all

Change the microscope

Look at the same onion peel in three ways.

Magnification

A microscope magnifies tiny objects so they become visible. Ordinary microscopes magnify about 100 to 400 times. An electron microscope magnifies about 10,00,000 times and reveals subcellular structures.

• Tool | Magnifies | What you see
• Eyes only | 1 time | A thin skin
• Ordinary microscope | About 100 to 400 times | Cells
• Electron microscope | About 10,00,000 times | Structures inside the cell

Notes

A microscope magnifies tiny objects so they become visible. Ordinary microscopes: about 100 to 400 times. Electron microscope: about 10,00,000 times, revealing subcellular structures.

Check yourself

A microscope magnifies 100 times. A tiny object is 2 mm long. How long does it look through the microscope?

Answer: 200 mm

2 mm × 100 = 200 mm.

Which instrument reveals structures inside a cell (subcellular structures)?

About how many times does an ordinary microscope magnify?

• An electron microscope — correct. Yes. It magnifies about 10,00,000 times.
• An ordinary microscope. An ordinary microscope magnifies about 100 to 400 times. It shows the cell but not the finer structures inside.
• About 100 to 400 times — correct. Yes. That is enough to see cells and microorganisms.
• About 10,00,000 times. That is an electron microscope.