Found 575 Articles for Physics

A Directional coupler is a device that samples a small amount of Microwave power for measurement purposes. The power measurements include incident power, reflected power, VSWR values etc. Directional coupler is used to couple the Microwave power which may be Uni-directional or bi-directional. It is a 4 port waveguide junction consisting of a Primary main waveguide and a Secondary auxiliary waveguide. The below figure shows the image of a directional coupler.PropertiesThe properties of an Ideal directional coupler are as follows.All the terminations are matched to the ports.When the power travels from port 1 to port 2, some portion of it ... Read More

Whenever a current carrying conductor is placed in a magnetic field, it experiences a force. The relation between these three is stated by Fleming’s left-hand rule. To understand this rule, the thumb, middle and index fingers are placed in perpendicular to each other.Thumb RuleImagine a current carrying conductor placed in-between a horseshoe magnet. This magnet produces some magnetic field which will be in the direction indicated by the forefinger or Index finger. The current passing through the conductor will be in the direction of the middle finger. This conductor experiences a force which is indicated in the direction of thumb. ... Read More

In Radio communication systems, we use wireless electromagnetic waves as the channel. The antennas of different specifications can be used for these purposes. The mode of propagation of electromagnetic waves in the atmosphere and in free space may be divided into the following three categories:The line of sight (LOS) propagationGround wave propagationSkywave propagationIn ELF (Extremely low frequency) and VLF (Very low frequency) frequency bands, the Earth, and the ionosphere act as a wave-guide for electromagnetic wave propagation. In these frequency ranges, communication signals practically propagate around the world. The channel bandwidths are small. Therefore, the information is transmitted through these ... Read More

The lens antenna uses a curved surface for the transmission or reception. Lens antennas are made up of glass, where the converging and diverging properties of the lens are followed. These are used for higher frequency applications greater at 3000 MHz and above.Working PrincipleIf a light source is assumed to be there at a focal point of a lens, which is at a focal distance from the lens, then the rays get through the lens as collimated or parallel rays on the plane wavefront.The rays that pass through the center of the lens are less refracted than the rays that ... Read More

The moving or Sailing stones are found in the Racetrack Playa, which is a dried lake bed, located in the Death Valley National Park of California where the Sailing stones move in a random fashion. Even the heaviest stones which weigh nearly 318 kilograms are moved.The rock trails were as long as 250 meters, while some trails are straight lines and some of them even have sudden bends and curves which baffled the researchers. There are no logical explanations for believing the reason such as wind or dust devils.A NASA scientist named Ralph Lorenz who is already investigating on weather ... Read More

It is a common question many have in mind. It is always important to ensure your safety by checking whether your house, office or workplace is properly earthed or not.The three-pin female plug pin present in the circuit board has three holes in it called as Phase (P), neutral (N) and Earth (E), as shown in the following picture.Take a light bulb holder, connected with two wires i.e., for positive and negative terminals of the bulb. Now insert one of the wires in phase and the other in neutral. The bulb glows indicating the power supply.Take out the wire from ... Read More

All things that fly using wings need air. Moving air has a force that will lift kites, airplanes, and balloons up and down. An aircraft experiences four basic forces, they areLift: The upward force acting on the aircraft which helps the airplane to fly.Drag: The backward force caused by the resistance of air flow.Thrust: The forward force produced by the engines of the aircraftWeight: The body and cargo weight of the aircraft acting in a downward direction.An aircraft flies when the lift force exceeds the weight of the aircraft. For this to happen the aircraft must move at high velocities. ... Read More

In the basic terminology in the system of limits and fits are a number of general definitions and terms which are used in the system of limits and fits.The terminologies are as follows:Shaft: Shaft can be defined as it is a member which can fit into another part with proper assembly of the part. A shaft can either rotate or be stationary. The shaft will be applied to a member which has to fit even if there is a restriction between two spaces.Hole: Hole can be defined as a member who can house or fit the shaft. A hole can ... Read More

Fits in metrology are the dimensional relation between the mating parts which are known as fits. It indicates that the tightness or the loosening of the mating parts. For engineering purposes, this is very important because it is used in real life applications for the satisfactory working of parts in movement such as a piston in a cylinder, journal in a bearing, gear on splines, a valve in a valve guide and wheel on a shaft.There are very important terms related to a fit which is:Clearance − Clearance in a fit is when the difference between the sizes of the ... Read More

Selective AssemblyThe selective assembly can be referred to as a concept where the subcomponents are assembled to form a proper final assembly which will in return provide the highest tolerance specification.Using selective assembly when the parts are being manufactured, the selective assembly resembles an old concept of inspection, in which the component is being identified as good or bad. If all the parts are correct and the component is good then it will be used for assembly or else it will be used for scrap purposes.In selective assembly, if the components are divided into different categories, then the groups will ... Read More