Forests cover about 31% of the land on Earth. Sadly, that number is decreasing at a rapid rate. Deforestation, which is human-driven and natural loss of trees, is one of the main causes of this depletion. A natural loss of trees might come from a fire, for example, but deforestation done by humans is more common and involves removing trees to make room for something else. This can include clearing land for farming or using the wood from trees for fuel, construction, or manufacturing. Despite these potential economic benefits, deforestation should be stopped because forests are too important for people, animals, and the environment. Write 3-5 sentences explaining what the key concept of the paragraph is and how the author develops the key concept.

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation: