fact of brahma marrige

Brahma marriage is regarded as the purest form of marriage in Hindu religion. As per the traditions of this marriage, the father gives his daughter to a man of learning and good character. The daughter is richly dressed and adorned with ornaments and is offered as a kind of gift, also referred as 'danam' to a man having good character and high learning, also known as 'srutisilavan'. It is considered to be the most honourable type of marriage according to the Smritis. The existence of Brahma marriage can be traced back to the Vedic era. 

Eligibility of Brahma Marriage 
A Brahma marriage is a type of Indian marriage where a boy is able to get married once he has completed his student hood, or Brahmacharya. Brahma marriage has the most supreme position of the eight types of marriages. In ancient days, there prevailed gurukul system, where the boy goes to live with his guru to acquire knowledge and expertise. This stage isBrahmacharya or student-hood for the boy and he would be eligible to get married only once he completes his studies. 

Arrangement of Brahma Marriage 
Once the boy is ready to get married after acquiring all the expertise required his parents would approach the family of a matching and eligible girl. The father of the girl also carefully chooses the bridegroom who is well versed in Vedas and of a noble character. This is how a Brahma marriage is arranged. 

Rituals of Brahma Marriage 
The girl's family did not have to give any dowry to the boy's family. There was the ritual of kanyadaan which symbolizes that the father gifts his daughter to the boy. In this system of marriage no commercial transaction is done. Among the eight types, this is regarded as the highest type of marriage by the dharmashastras. 

This marriage is performed even before the girl has attained her puberty. The mantras are chanted while performing the marriage, which are addressed by the groom to the bride who comes to him. It was understood that a girl's marriage, which has same significance for her that the upanayana has for a boy, must be performed when she is seven years old (or eight years from conception). 

Problem 9.8 Orthographic Projection

Problem 9.8 Orthographic Projection – Draw the Orthographic Projections of the object given below in 1^stangle method of projection. (1) Front View (2) Top View (3) L.H. S.V.

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Procedure:

Step-1 Draw a horizontal x-y line of some suitable length. And x’-y’ line perpendicular to preciously drawn x-y line and give the point O at the intersection of the two lines.

Step-2 In this problem the Front View, Top View and Left Hand Side View have to be drawn in 1st angle method of projection, so first find out the total length, total height and total width from the isometric drawing given above. The total length is the length of the base of the front view, i.e., form X direction. The total height is the height in the front view and the total width is the length of the base in the side view.

Step-3 The total length is 105 mm, total height is 75 mm and the total width is 80 mm.

Step-4 Draw three boxes with light straight lines at respective location in such a way that the views should be in 1st angle method of projection. And these boxes should be at least 10 mm away from the x-y & x’-y’ lines.

Step-5 Then start the drawing by front view and within the respective box with dimensions, and it should be drawn with medium dark lines or curves. Like in this way draw all the required view and look for the hidden lines, which are drawn as dashed line. But the drawing should be drawn by transferring the projectors only wherever possible.

Step-6 Give the dimensions by any one method of dimensions and give the name of the views, as shown in the figure.

Right Hand Thumb Rule:

The direction of magnetic field; in relation to direction of electric current through a straight conductor can be depicted by using the Right Hand Thumb Rule. It is also known as Maxwell’s Corkscrew Rule.

If a current carrying conductor is held by right hand; keeping the thumb straight and if the direction of electric current is in the direction of thumb, then the direction of wrapping of other fingers will show the direction of magnetic field.

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As per Maxwell’s corkscrew rule, if the direction of forward movement of screw shows the direction of current, then the direction of rotation of screw shows the direction of magnetic field.

Properties of Magnetic Field:

• The magnitude; of magnetic field increases with increase in electric current and decreases with decrease in electric current.
• The magnitude of magnetic field; produced by electric current; decreases with increase in distance and vice-versa. The size of concentric circles of magnetic field lines increases with distance from the conductor, which shows that magnetic field decreases with distance.
• Magnetic field lines are always parallel to each other.
• No two field lines cross each other.

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Magnetic field due to current through a circular loop:

In case of a circular current carrying conductor, the magnetic field is produced in the same manner as it is in case of a straight current carrying conductor.

In case of a circular current carrying conductor, the magnetic field lines would be in the form of concentric circles around every part of the periphery of the conductor. Since, magnetic field lines tend to remain closer when near the conductor, so the magnetic field would be stronger near the periphery of the loop. On the other hand, the magnetic field lines would be distant from each other when we move towards the centre of the current carrying loop. Finally; at the centre, the arcs of big circles would appear as a straight lines.

The direction of magnetic field can be identified using Right Hand Thumb’s Rule. Let us assume that the current is moving in anti-clockwise direction in the loop. In that case, the magnetic field would be in clockwise direction; at the top of the loop. Moreover, it would be in anticlockwise direction at the bottom of the loop.

Clock Face Rule: A current carrying loop works like a disc magnet. The polarity of this magnet can be easily understood with the help of clock face rule. If the current is flowing in anti-clockwise direction, then the face of the loop shows north pole. On the other hand, if the current is flowing in clockwise direction, then the face of the loop shows south pole.

Magnetic field and number of turns of coil: Magnitude of magnetic field gets summed up with increase in the number of turns of coil. If there are ‘n’ turns of coil, magnitude of magnetic field will be ‘n’ times of magnetic field in case of a single turn of coil.

Magnetic Field due to a current in a Solenoid:

Solenoid is the coil with many circular turns of insulated copper wire wrapped closely in the shape of cylinder.

A current carrying solenoid produces similar pattern of magnetic field as a bar magnet. One end of solenoid behaves as the north pole and another end behaves as the south pole. Magnetic field lines are parallel inside the solenoid; similar to a bar magnet; which shows that magnetic field is same at all points inside the solenoid.

By producing a strong magnetic field inside the solenoid, magnetic materials can be magnetized. Magnet formed by producing magnetic field inside a solenoid is called electromagnet.

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Electromag Induction

Insulator Breakdown Voltage

Chapter 12 - Physics Of Conductors And Insulators

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The atoms in insulating materials have very tightly-bound electrons, resisting free electron flow very well. However, insulators cannot resist indefinite amounts of voltage. With enough voltage applied, any insulating material will eventually succumb to the electrical “pressure” and electron flow will occur. However, unlike the situation with conductors where current is in a linear proportion to applied voltage (given a fixed resistance), current through an insulator is quite nonlinear: for voltages below a certain threshold level, virtually no electrons will flow, but if the voltage exceeds that threshold, there will be a rush of current.

Once current is forced through an insulating material, breakdown of that material’s molecular structure has occurred. After breakdown, the material may or may not behave as an insulator any more, the molecular structure having been altered by the breach. There is usually a localized “puncture” of the insulating medium where the electrons flowed during breakdown.

Thickness of an insulating material plays a role in determining its breakdown voltage, otherwise known asdielectric strength. Specific dielectric strength is sometimes listed in terms of volts per mil (1/1000 of an inch), or kilovolts per inch (the two units are equivalent), but in practice it has been found that the relationship between breakdown voltage and thickness is not exactly linear. An insulator three times as thick has a dielectric strength slightly less than 3 times as much. However, for rough estimation use, volt-per-thickness ratings are fine.

                  

Faraday's Law Any change in the magnetic environment of a coil of wire will cause a voltage (emf) to be "induced" in the coil. No matter how the change is produced, the voltage will be generated. The change could be produced by changing the magnetic field strength, moving a magnet toward or away from the coil, moving the coil into or out of the magnetic field, rotating the coil relative to the magnet, etc. Further comments on these examples Faraday's law is a fundamental relationship which comes from Maxwell's equations. It serves as a succinct summary of the ways a voltage (or emf) may be generated by a changing magnetic environment. The induced emf in a coil is equal to the negative of the rate of change of magnetic flux times the number of turns in the coil. It involves the interaction of charge with magnetic field. Lenz's law AC coil example Faraday's Law and Auto Ignition

Index Faraday's Law concepts

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Lenz's Law When an emf is generated by a change in magnetic flux according to Faraday's Law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it. The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant. In the examples below, if the B field is increasing, the induced field acts in opposition to it. If it is decreasing, the induced field acts in the direction of the applied field to try to keep it constant.

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