(a) Explain the meaning of the terms negative and positive feedback as they apply to amplifier circuits. Briefly describe one application of positive feedback that you have encountered.
(b) Outline three advantages of employing negative feedback in an operational amplifier circuit. Why is it often necessary to reduce the gain of an operational amplifier from its open-loop value?
(c) Derive an expression for the voltage gain of an amplifier employing voltage series negative feedback and thus show that the closed-loop gain is independent of the open- loop gain, provided that certain conditions are obeyed: list the necessary conditions
(d) If the open-loop gain of an amplifier of this type is 4 x 10^5, and the fraction of the output voltage fed back to the input is 0.01, calculate the change in gain of the feedback amplifier if the open-loop gain changes by 30%.

so here is the information for current research:

-nrel's geothermal analysts, scientists, and engineers perform a full range of research from developing advanced methods of locating and accessing geothermal resources to exploring innovative technologies to extract and produce clean energy from the heat of the earth

and here is the information for the technology of geothermal energy:

-it's clean and sustainable

-resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma

-almost everywhere, the shallow ground or upper 10 feet of the earth's surface maintains a nearly constant temperature between 50° and 60°f (10° and 16°c)

-geothermal heat pumps can tap into this resource to heat and cool buildings

-a geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building

-in the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system

-in the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger

-the heat removed from the indoor air during the summer can also be used to provide a free source of hot water

  the unit of the measure =

explanation:

  the property that is quantified by the energy needed per of material to raise the temperature by one.

  si unit of energy = joule (j)

  si unit of temperature = kelvin (k)

  si unit of mass of material = kilogram (kg)

the property that is quantified by the energy needed per of material to raise the temperature by one is called specific heat.

the unit of specific heat is