Apenny has a mass of 3.0 g, a diameter of 1.9 cm, and a thickness of 0.15 cm. what is the density of the metal of which it is made?

To calculate the density of an object, we must divide its mass by its volume.
For the case of the given penny, since it is cylindrical in form, then to solve for the volume, we have . Since the penny has a diameter of 1.9 cm, then it has radius of 1.9/2 = 0.95 cm. 
Thus, its volume is
Now to get the density, we have

Therefore, the penny's density is .

Answerwavelength;

The modern-day generator works on the principle of electromagnetic induction discovered by michael faraday in 1831-32. faraday discovered that the above flow of electric charges could be induced by moving an electrical conductor, such as a wire that contains electric charges, in a magnetic field.