Electron microscopes have certain advantages over optical microscopes: The biggest advantage is that they have a higher resolution and are therefore also able of a higher magnification (up to 2 million times). Light microscopes can show a useful magnification only up to 1000-2000 times. This is a physical limit imposed by the wavelength of the light. Electron microscopes therefore allow for the visualization of structures that would normally be not visible by optical microscopy.
berm (plural berms) A narrow ledge or shelf, as along the top or bottom of a slope. A raised bank or path, especially the bank of a canal opposite the towpath. A terrace formed by wave action along a beach. A mound or bank of earth, used especially as a barrier or to provide insulation.
Natural gas is measured in therms or BTUs. A therm is a measurement of the amount of heat energy in natural gas, equal to 100,000 BTUs. A BTU, or British Thermal Unit, is the quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit. The current charge for natural gas from Peoples Gas is $0.2958 per therm. If you would like to change the rate used in the calculations above, enter a new rate below. $ per therm.