Ebtesam Abdullah
130137304
Informational document
Microwave
The title is clear and easy
to understand
Introduction:
Introduction provides appropriate
level of detail for first-time users.
technology is the making, modification, usage, and knowledge of tools,
machines, techniques, crafts, systems, and methods of organization, to
solve a problem, improve an existing solution to a problem, achieve a
goal, or perform a specific function. Technologies are also the collection
of such tools, including machinery, modifications, arrangements and
procedures. Technologies significantly affect human as well as other
animal species' ability to control and adapt to their natural environments.
The human species' use of technology began with the conversion of
natural resources into simple tools. The prehistoric discovery of how to
control fire increased the available sources of food and the invention of
the wheel helped humans in travelling in and controlling their
environment. Recent technological developments, including the printing
press, the telephone, and the Internet, have lessened physical barriers to
communication and allowed humans to interact freely on a global scale.
What is microwave?
User-centered heading are phrased as
questions that readers would need
answered.
A microwave oven, commonly referred to as a microwave, is
a kitchen appliance that heats and cooks food by bombarding it
with electromagnetic radiation in the microwave
spectrum causing polarized molecules in the food to rotate and
build up thermal energy in a process known as dielectric heating.
Microwave ovens heat foods quickly and efficiently because
excitation is fairly uniform in the outer25–38 mm (1–1.5 inches) of
a dense (high water content) food item; food is more evenly heated
throughout (except in thick, dense objects) than generally occurs in
other cooking techniques.
Percy Spencer invented the first microwave oven after World War
II from radar technology developed during the war. Named the
"Radarange", it was first sold in 1946. Raytheon later licensed its
patents for a home-use microwave oven that was first introduced
by Tappan in 1955, but these units were still too large and
expensive for general home use. The countertop microwave oven
was first introduced in 1967 by the Amana Corporation, and their
use has spread into commercial and residential kitchens around
the world.
Technical design of the oven microwave:
A microwave oven consists of:
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
a high voltage power source, commonly a simple transformer or
an electronic power converter, which passes energy to the
magnetron
a high voltage capacitor connected to the magnetron,
transformer and via a diode to the chassis
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a cavity magnetron, which converts high-voltage electric energy
to microwave radiation
a magnetron control circuit (usually with a microcontroller)
a short waveguide (to couple microwave power from the
magnetron into the cooking chamber)
a metal cooking chamber
a turntable or metal fan
Effects on food and nutrients
Heading and clean layout
make this document easy for
readers
Raisins when overcooked in a microwave produce considerable smoke
Comparative cooking method studies generally find that, if properly used,
microwave cooking does not affect the nutrient content of foods to a
larger extent than conventional heating, and that there is a tendency
towards greater retention of many micronutrients with microwaving,
probably due to the reduced preparation time. Microwaving human milk
at high temperatures is contraindicated, due to a marked decrease in
.activity of anti-infective factors
Any form of cooking will destroy some nutrients in food, but the key
variables are how much water is used in the cooking, how long the food
is cooked, and at what temperature. Nutrients are primarily lost by
leaching into cooking water, which tends to make microwave cooking
healthier, given the shorter cooking times it requires. Like other heating
methods, microwaving converts vitamin B12 from an active to inactive
form. The amount inactivated depends on the temperature reached, as
well as the cooking time. Boiled food reaches a maximum of 100 °C (212
°F) (the boiling point of water), whereas microwaved food can get locally
hotter than this, leading to faster breakdown of vitamin B12. The higher
rate of loss is partially offset by the shorter cooking times required. A
single study indicated that microwaving broccoli loses 74% or more of
phenolic compounds (97% of flavonoids), while boiling loses 66% of
flavonoids, and high-pressure boiling loses 47% though the study has
been contradicted by other studies. To minimize phenolic losses in
potatoes, microwaving should be done at 500W.
Illustrations combine text
and visual
Benefits and safety features
Commercial microwave ovens all use a timer in their standard operating
mode; when the timer runs out, the oven turns itself off.
Microwave ovens heat food without getting hot themselves. Taking a pot
off a stove, unless it is an induction cook top, leaves a potentially
dangerous heating element or trivet that will stay hot for some time.
Likewise, when taking a casserole out of a conventional oven, one's arms
are exposed to the very hot walls of the oven. A microwave oven does not
pose this problem.
Food and cookware taken out of a microwave oven are rarely much hotter
than 100 °C (212 °F). Cookware used in a microwave oven is often much
cooler than the food because the cookware is transparent to microwaves;
the microwaves heat the food directly and the cookware is indirectly
heated by the food. Food and cookware from a conventional oven, on the
other hand, are the same temperature as the rest of the oven; a typical
cooking temperature is 180 °C (356 °F). That means that conventional
stoves and ovens can cause more serious burns.
The lower temperature of cooking (the boiling point of water) is a
significant safety benefit compared to baking in the oven or frying,
because it eliminates the formation of tars and char, which
are carcinogenic.[29] Microwave radiation also penetrates deeper than
direct heat, so that the food is heated by its own internal water content. In
contrast, direct heat can fry the surface while the inside is still cold. Preheating the food in a microwave oven before putting it into the grill or
pan reduces the time needed to heat up the food and reduces the
formation of carcinogenic char. Unlike frying and baking, microwaving
does not produce acryl amide in potatoes however unlike deep-frying, it
is of only limited effectiveness in reducing glycoalkaloid (i.e. solanine)
levels. Acryl amide has been found in other microwaved products like
popcorn..
Summary:
Technical writing helps to make the information in the document
concept in a simple way and understandable without long detail and
helps the reader to understand the topic without the trouble .
Reference see to http://en.wikipedia.org/wiki/Microwave_oven