1. Why can we not use a simple microscope to see objects as small as we want, an
ID: 1415672 • Letter: 1
Question
1. Why can we not use a simple microscope to see objects as small as we want, and use a telescope to see things as far away as we want?
2. The four fundamental forces of nature are – gravity, electromagnetic, strong and weak force. All the forces that we experience in our daily lives (e.g. tension, pull, push, weight, etc.) belong to one of these. List some other familiar forces that you can think of, and classify them – which category of fundamental forces do they belong to. Also, point out some important similarities and differences between the electromagnetic and gravitational forces.
Explanation / Answer
1) We can’t see an unlimited amount of detail down a microscope. Any object that’s less than half the wavelength of the microscope’s illumination source is not visible under that microscope.
If we look at a far-away object, the image of the object will form a diffraction pattern on our retina. For two far-away objects separated by a small angle, the diffraction patterns will overlap. We are able to resolve the two objects as long as the central peaks in the two diffraction patterns don't overlap .
2) gravity - force between human and earth .
electromagnetic - force between magnets .
strong and weak force - force between block and rope .
Gravitational forces, are generated by the bulk motion of large masses, and will have wavelengths much longer than the objects themselves. Electromagnetic forces, are typically generated by small movements of charge pairs within objects, and have wavelengths much smaller than the objects themselves.
Another difference between the two forces is the fact that gravitation only attracts, while electrical forces attract when the electrical charges are opposite and repel if the charges are similar. Thus, gravitation is considered a monopole force, while electrostatics is a dipole force.
Besides being proportional to the inverse of the square of the separation, both forces extend to infinity. They also both travel at the speed of light.
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