Question

Place the ruler on the stage of microscope, focus on it using the adjustment knob and observe the diameter of the circular field of view through the eyepiece and measure it in mm.

Convert the diameter from mm to micrometre (µm). Suppose the diameter of the visible field is 5 mm, meaning 5 × 1000 = 5000 µm.

Robert Hooke, in 1665, looked at a thin slice of a plant material through his microscope and saw tiny box-like compartments, which he called 'cells'. Which material did he observe?