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What is a critical angle and when does total internal reflection take place?

When a ray of light travels from a denser medium to a rarer medium it bends away from the normal. It the angle of incidence is too large, the angle of refraction will be very large as well (It can be proved ...
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Answered by Swapnil S. • Physics tutor
10570 Views

How can I integrate e^x sinx?

Such an integral looks difficult to manage; clearly it is a case of integration by parts, but neither part of the product appears to reduce easily into a nicer form. The key here is use the fact that sinx ha...
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Answered by Alex W. • Maths tutor
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Why is the "No False Lemmas" approach an inadequate repair to the JTB account of knowledge?

It has been shown that replacing the justification condition in the classical account of knowledge is neither necessary, nor sufficient, to grant a person knowledge. Consider a person driving through 'Barn F...
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Answered by Alex W. • Philosophy tutor
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What is electromotive force and how is it different to potential difference?

The electromotive force or emf of a cell in a circuit is, for a start, not a force at all: it has the unit of volts. A good definition is ‘the power supplied by the cell per unit current through the cell’ or...
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Answered by Tom B. • Physics tutor
12766 Views

When do you use 'n choose k' and where does the formula come from?

When do you use n choose k ? Say you have n objects/elements, and each one can either be selected or not selected. ‘ n choose k ’ gives you the number of different ways in which you can end up with k selecte...
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Answered by Tom B. • Maths tutor
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