For the circuit in Fig. 12.40(b), let V, V, I = 20 A, and . Find the input common-mode range and the differential voltage gain . Neglect base currents.
Lecture 4 What is a Year o Tropical or Solar Year Time difference between spring equinox 365.242 o Sidereal Year Orbit Sun once with respect to distant starts 365.256 days o Timing of equinox in the orbit is changing One view of Water: o A series of inputs and outputs, climatic and human Inputs: Precipitation (22% over land, snow, and rainfall) Infiltration (water that makes it through the soil) Percolation (water from soil to rock and subsurface runoff overland flow, streams) o Outputs: Evaporation (Loss of water from surface) Transpiration (Water loss from plants) Evapotranspiration includes both terms ~14% of global evapotranspiration is over land Potential Evaporation (PET or POTET): o The amount of water that would evaporate under optimum conditions o If there was water, how much would evapotranspire o Actual Evapotranspiration (AET or ACTET) Determined by subtracting a “deficit” (DEFIC) from the POTET Storage: o Moisture exists in soil in three forms o Hygroscopic Water is a molecular layer attached to soil particles and is not available for use o Capillary Water is held within the soil and IS AVAILABLE for withdrawal from the savings account o Gravitational Water is big surplus; it saturates the soil and recharges groundwater The Natural Balance Evapotranspiration = Transpiration + Evaporation Balance Utilization is withdrawal, recharge is a deposit Groundwater: Lies beneath the Earth’s surface between 0 and 13,00 feet depth Usable groundwater is “stored” (found) in aquifers Aquifers: o Zone of aeration is the area just beneath the surface air pockets allow water to move through capillary action o Zone of saturation is here all the soil pore spaces contain water o Water table is the contact point between zone of aeration and zone of saturation o Permeability refers to whether or not soil/rock can permit water flow o Aquifer is a rock layer that is permeable to groundwater flows in usable amounts o Influent vs Effluent describes the interaction between the water table and surface streams Aquifers and Human Modifications: Groundwater pumping can change the aquifer “drawdown” Area where the water table is lowered takes the form of a “cone of depression” When water is pumped faster than it can be recharged, it’s called “groundwater mining” Aquifers can collapse when they lose the support of water this creates a problem with subsidence Aquifer Examples: Ogallala Aquifer: o Largest known aquifer in the world 174,000 mi cubed BILLIONS of dollars in agriculture activity o Retreating glaciers from Ice Ages charged it up for several hundred thousand years o In the past 100 years, we’ve dropped the water table about 100ft Drought: A physical and social construct Meteorological Drought Dry conditions of low and precipitation and high temperature Agricultural Drought Soilmoisture and weather affect crop production Hydrologic Drought Water supply (streams, reservoirs, groundwater) drops Socioeconomic Drought Comprehensive measure...not enough water to meet demand of plants, animals, and humans