ANGLE OF DIP

Magnetic Compass
A magnet is a piece of iron, steel or steel alloy that was induced by a magnetic field. A magnet will attract similar metals. Some steel alloys have the quality to retain magnetism forever, thus forming permanent magnets. When a magnetized needle is suspended on a pivot, the North Magnetic Pole attracts one end of the needle while the other end is attracted to the South Magnetic Pole. A magnetic compass is an instrument that measures the direction relative to the magnetic north pole.

Magnetic Dip
At the magnetic equator, the attraction of the compass needle towards the north and south poles is equal and the needle remains unbiased. As the compass is moved either north or south of the magnetic equator, the attraction to the nearest pole is increased, thus the needle will be biased towards the nearest pole. This phenomenon is called magnetic dip.

WORKING OF CAPACITOR

When a voltage is applied across the two plates of a capacitor, a concentrated field flux is created between them, allowing a significant difference of free electrons (a charge) to develop between the two plates: As the electric field is established by the applied voltage, extra free electrons are forced to collect on the negative conductor, while free electrons are "robbed" from the positive conductor. This differential charge equates to a storage of energy in the capacitor, representing the potential charge of the electrons between the two plates. The greater the difference of electrons on opposing plates of a capacitor, the greater the field flux, and the greater "charge" of energy the capacitor will store.

When the voltage across a capacitor is increased, it draws current from the rest of the circuit, acting as a power load. In this condition the capacitor is said to be charging, because there is an increasing amount of energy being stored in its electric field. Note the direction of electron current with regard to the voltage polarity:

PICTURES OF CAPACITORS

CAPACITOR

Electric fields and capacitance
Whenever an electric voltage exists between two separated conductors, an electric field is present within the space between those conductors. In basic electronics, we study the interactions of voltage, current, and resistance as they pertain to circuits, which are conductive paths through which electrons may travel. When we talk about fields, however, we're dealing with interactions that can be spread across empty space. Capacitors are components designed to take advantage of this phenomenon by placing two conductive plates (usually metal) in close proximity with each other. There are many different styles of capacitor construction, each one suited for particular ratings and purposes. For very small capacitors, two circular plates sandwiching an insulating material will suffice. For larger capacitor values, the "plates" may be strips of metal foil, sandwiched around a flexible insulating medium and rolled up for compactness. The highest capacitance values are obtained by using a microscopic-thickness layer of insulating oxide separating two conductive surfaces. In any case, though, the general idea is the same: two conductors, separated by an insulator.
The schematic symbol for a capacitor is quite simple, being little more than two short, parallel lines When a voltage is applied across the two plates of a capacitor, a concentrated field flux is created between them, allowing a significant difference of free electrons (a charge) to develop between the two plates:

ASSIGNMENT ----CAPACITOR

Q1) If the plates of a capacitor are suddenly connected to each other by a wire, what will happen?
Q) The distance between the plates of a capacitor is d. A metal plate of thickness d/2 is placed between the plates; what will be the effect on the capacitance?
Q) Is there any material which when inserted b/w the plates of a capacitor reduces its capacitance?

Q) The plates of a capacitor are connected by a voltmeter. If the plates are moved further apart what will be the effect on the reading of voltmeter?

Q) Sketch graph to show how the capacitance of a capacitor varies with charge given to it.

Q) A charged air capacitor has energy stored U. What will be the energy stored air is replaced by a dielectric of constant "K" ; CHARGE remaining same.

Q) Why does the polarization of dielectric reduce the electric field inside it?

Q) What happens to the energy stored in a capacitor when the plates of charged capacitor are moved farther after -------a) connecting , b) disconnecting the battery.

Q) Two capacitor C-1 and C-2 are connected in parallel. A charge 'q' is given to this combination.What will be the p.d. across each capacitor?

Q) Two spheres of Cu of same radii--- one hollow and other solid are charged to same potential. Which possesses more charge?

TOTAL INTERNAL REFLECTION PART-2

A beam of light travels from water into a piece of diamond in the shape of a triangle, as shown in the diagram. Step-by-step, follow the beam until it emerges from the piece of diamond

(a) How fast is the light traveling inside the piece of diamond?
The speed can be calculated from the index of refraction:
(b) What is , the angle between the normal and the beam of light inside the diamond at the water-diamond interface?
A diagram helps for this. In fact, let's look at the complete diagram of the whole path, and use this for the rest of the questions. The angle we need can be found from Snell's law:
(c) The beam travels up to the air-diamond interface. What is , the angle between the normal and the beam of light inside the diamond at the air-diamond interface?
This is found using a bit of geometry. All you need to know is that the sum of the three angles inside a triangle is 180°. If is 24.9°, this means that the third angle in that triangle must be 25.1°. So:
(d) What is the critical angle for the diamond-air interface?

(e) What happens to the light at the diamond-air interface?
Because the angle of incidence (64.9°) is larger than the critical angle, the light is totally reflected internally.
(f) The light is reflected off the interface, obeying the law of reflection. It then strikes the diamond-water interface. What happens to it here?
Again, the place to start is by determining the angle of incidence
Because the angle of incidence is less than the critical angle, the beam will escape from the piece of diamond here. The angle of refraction can be found from Snell's law:

TOTAL INTERNAL REFLECTION

Total internal reflection is an optical phenomenon that occurs when a ray of light strikes a medium boundary at an angle larger than the critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary no light can pass through, so effectively all of the light is reflected. The critical angle is the angle of incidence above which the total internal reflection occurs.
When light crosses a boundary between materials with different refractive indices, the light beam will be partially refracted at the boundary surface, and partially reflected. However, if the angle of incidence is greater (i.e. the ray is closer to being parallel to the boundary) than the critical angle — the angle of incidence at which light is refracted such that it travels along the boundary — then the light will stop crossing the boundary altogether and instead be totally reflected back internally. This can only occur where light travels from a medium with a higher refractive index to one with a lower refractive index. For example, it will occur when passing from glass to air, but not when passing from air to glass.