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What is the difference between reflection, refraction and diffraction?

These are all properties of waves and their definitions are useful to remember for exams. It can also be helpful to draw diagrams of each to help you to remember the difference. On the diagram it is useful t...
AK
Answered by Anna K. • Physics tutor
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Expand and simplify 3(2x + 5) – 2(x – 4)

Firstly, to expand an equation like this, you must multiply the brackets by the number outside of the brackets. Make sure that you multiply every number inside the bracket by the number directly outside, and...
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Answered by Anna K. • Maths tutor
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Explain the Chain Rule

The chain rule is used to differentiate composite functions, ie "a function of a function". In this case we have an outer function and an inner function. For example Differentiate f(g(x)). Here f i...
AC
Answered by Alex C. • Maths tutor
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What is the angle between the position vectors a and b, where a = (6i - j + 3k) and b = (-4i + 2j + 10k)?

cos( AOB ) = a.b /(| a | x | b |) a.b = (6i - j + 3k) . (-4i + 2j + 10k) = (6 x -4) + (-1 x 2) + (3 x 10) = -24 + -2 + 30 = 4 (| a |)^2 = 6^2 + (-1)^2 + 3^2 = 36 + 1 + 9 = 46 -> | a | = 46^(1/2) (| b |)^2...
DH
Answered by David H. • Maths tutor
6718 Views

What is the myelin sheath?

The myelin sheath is a layer of insulating, fatty material that encases some neurones. The sheath is composed of Schwann cells that have gaps called nodes of Ranvier between them. Potassium and sodium ions c...
AH
Answered by Alice H. • Biology tutor
5333 Views