^Maxwell equations
^Maxwell equations
Following five equations give a complete description of all em– interactions and are called Maxwell eq:
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^ γ-rays
^γ – rays
(a) Produced in nuclear reactions and are also emitted by radioactive nuclei (such as Co 60 & Cs 137).
(b) Properties: Effect on photographic plate, fluorescence, ionization, diffraction, high penetrating power & can cause serious damage if absorbed by living tissues.
(c) Used
- in radio therapy to treat certain cancers and tumors
- to produce nuclear reactions
- to study the atomic nuclei.
^Ultraviolet light
^Ultraviolet light
(a) Produced by special lamps like mercury and iron are lamps and by very hot bodies like sun.
(b) Properties: Effect on photographic plate, fluorescence, ionization, highly energetic, tanning of the human skin.
(c) Used
- To destroy bacteria and for sterilizing the surgical instruments
- In the detection of forged documents finger prints
- In burglar alarms etc as they can cause photoelectric effect.
- For studying fluorescence
- In the study of molecular structure and arrangement of electrons
- To prevent the food stuff.
^Visible light
^Visible light
- Produced by hot bodies like sun, electric bulbs and tubes etc. as a result of electronic transitions. Our eyes are sensitive to visible light which helps us to collect the information about our surrounding.
- Properties: Reflection, refraction, interference, diffraction, polarization, photoelectric effect, photographic action, sensation of sight.
^Infra red waves
^Infra red waves
(a) Also called heat waves & are produced by hot bodies and molecules.
(b) Properties: Heating effect, reflection, refraction, diffraction & propagation through fog.
(c) Used
- In taking photographs during the conditions of fog, smoke etc. as these waves are scattered less than visible rays and hence can travel longer distances through atmosphere under fog, smoke etc.
- In weather forecasting
- In checking the purity of chemicals
- In the study of molecular structures
- For producing dehydrated fruits
- In green houses to keep the plants warm
- To provide electrical energy to satellites using solar cells.
- To treat muscular strain.
- In solar water heaters and cookers.
*Average acceleration
*Average acceleration
Average acceleration is defined as the change in the velocity per unit time spent. If the velocity of a moving body a time t1 when it was at point A is v1. Let at time t2 it reaches point B where is velocity is v2.
Change in its velocity per unit time spent is called average acceleration for an interval.
For motion along x – axis,
^Position of an arbitrary point P at any time is described using cartesian coordinates i.e. P (x,y, z).
Position
^Position of an arbitrary point P at any time is described using cartesian coordinates i.e. P (x,y, z).
For 1 D motion along x axis, y & z coordinates are zero, where as x coordinate may be + ve or – ve.
1, 2 & 3 – D motion
If coordinate required to specify the position of a moving object at any instant are;
- then motion is called 1 D e.g. moving along a straight line without turning.
- then motion is called 2 D e.g. an object moving along a circle.
- then motion is called 3 D e.g. random motion of gas particles
^Two series cells in oppostions
Two series cells in oppostions
As the two cells are opposing thus
ξnet =ξ1 – ξ2 , rnet = r1 + r2
V1 = ξ1 – Ir1, V2 = ξ2 + I r2
^A long horizontal fixed wire carries a current of 100 A. Directly above and parallel to it is another wire carrying a current of 20 A and weighing 0.04 N/m.
^A long horizontal fixed wire carries a current of 100 A. Directly above and parallel to it is another wire carrying a current of 20 A and weighing 0.04 N/m. The separation between the two wires so that the upper wire is just supported by the magnetic repulsion is
