physics-fun

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OPTIC ROTATION

PLANE POLARISED LIGHT This page gives a simple explanation of what plane polarised light is and the way it is affected by optically active compounds. A simple analogy - "plane polarised string" Imagine tying a piece of thick string to a hook in a wall, and then shaking the string vigorously. The string will be vibrating in all possible directions - up-and-down, side-to-side, and all the directions in-between - giving it a really complex overall motion. Now, suppose you passed the string through a vertical slit. The string is a really snug fit in the slit. The only vibrations still happening the other side of the slit will be vertical ones. All the others will have been prevented by the slit. What emerges from the slit could be described as "plane polarised string", because the vibrations are only in a single (vertical) plane. Now look at the possibility of putting a second slit on the string. If it is aligned the same wa

Cross Product

Cross Product In mathematics and vector calculus, the cross product or vector product (occasionally directed area product to emphasize the geometric significance) is a binary operation on two vectors in three-dimensional space (R3) and is denoted by the symbol ×. Given two linearly independent vectors a and b, the cross product, a × b, is a vector that is perpendicular to both and therefore normal to the plane containing them. It has many applications in mathematics, physics, engineering, and computer programming. It should not be confused with dot product (projection product). If two vectors have the same direction (or have the exact opposite direction from one another, i.e. are not linearly independent) or if either one has zero length, then their cross product is zero. More generally, the magnitude of the product equals the area of a parallelogram with the vectors for sides; in particular, the magnitude of the product of two perpendicular vectors is the product of thei

Adding vectors & scalars

Scalars adding two or more scalars quantities is a simple thing and can be done by simple law of addition . like in this example. A man walks 3km east and 4km north thus his total distance is 3km + 4km= 7km as distance is a scalar quantity so simple law of addition can be used . Vectors 1. Addition of vectors Two or more vectors may be added together to produce their ADDITION . If two vectors have the same direction, their resultant has a magnitude equal to the sum of their magnitudes and will also have the same direction. Similarly orientated vectors can be subtracted the same manner. It follows that vectors can also be multiplied by a scalar, so for example if the vector A were multiplied by the number m , the magnitude of the vector, |A| , would increase to m|A| , but its direction would not change. In general, since vectors may have any direction, we must use one of three methods for adding vectors. These are, the POLYGON METHOD

Scalar & Vectors Explained

we can divide physical quantities into 2 part vectors are physical quantities in physics which have both magnitude and direction.While scalars are that quantities which only have magnitude as their sole property. To explain better there is an example a person a is facing towards south he moves towards south for an hour and then takes a turn towards west and the again moves for an hour so he actually distance travelled is 500mi+100mi=600mi which is depicted by the black lines . The actual distance travelled ie 600m is dependent of the path followed and so independent of direction.As if he had travelled straight instead of turning right distance travelled would be same. So it is a scalar quantity now if we are calculating the displacement be the man it is root of 500^2 +100^2 (calculated by phythogoras theoram).Now displacement is the length of path formed by joining the start point and end point. Depicted by the red line in the digra