The thickness of the given circle made of the sample gold is 77.4 microns.
We know, the density of a material is the ratio of the mass of the material to the volume of the material.
Density = mass/volume
Therefore, volume = mass/density
Here, the density of the gold = 19.3 gm/cm³
Mass of the gold is = 285 mg = 0.285 gm
Therefore, the volume of the given gold is
= mass/density
= 0.285/19.3 cm³
= 0.0148 cm³
The circular sheet of gold has a radius of 0.78 cm.
Therefore, the area of the circular sheet is
= πr² cm²
= π(0.78)² cm²
= 1.911 cm²
Therefore, the thickness of the circular sheet is
= volume of the sheet/ area of the sheet
= 0.0148 cm³/ 1.911 cm²
= 7.74 × 10⁻³ cm
= 7.74 × 10⁻⁵ m
= 77.4 × 10⁻⁶ m
= 77.4 microns
Learn more about the volume of a material here: brainly.com/question/9214759
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