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SCIENCES
Cycle: One complete repeat of the pattern/vibration
Period: The time required to complete one cycle. (unit is s)
Amplitude: The distance from the equilibrium position (resting position) to the maximum displacement when in motion.
Frequency: the reciprocal of period (unit is Hz: 1 Hz = 1 s -1).
Wavelength: the length of one complete wave cycle.
A wave is a disturbance of a medium which transports energy through the medium without permanently transporting matter. In a wave, particles of the medium are temporarily displaced and then return to their original position. There are a variety of ways to categorize waves. One way to categorize waves is to say that there are longitudinal and transverse waves.
In a transverse wave, particles of the medium are displaced in a direction perpendicular to the direction of energy transport.
In a longitudinal wave, particles of the medium are displaced in a direction parallel to energy transport. The animation below depicts a longitudinal pulse in a medium.
The animation portrays a medium as a series of particles connected by springs. As one individual particle is disturbed, it transmits the disturbance to the next interconnected particle. This disturbance continues to be passed on to the next particle. The result is that energy is transported from one end of the medium to the other end of the medium without the actual transport of matter. In this type of wave - a longitudinal wave - the particles of the medium vibrate in a direction parallel to the direction of energy transport. More...
We can calculate the speed of a transverse wave on a stretched string as follows:
v2 = Ft / μ, μ = m/L
Consider an elastic rope stretched from end to end. One end will be securely attached to a pole on a lab bench while the other end will be held in the hand in order to introduce pulses into the medium. Because the right end of the rope is attached to a pole, the last particle of the rope will be unable to move when a disturbance reaches it. This end of the rope is referred to as a fixed end.
In order to be in phase, or out of phase, two waves must have the same frequency. When two waves are in phase, they oscillate together, their functions reach 0 value for same x values which repeat periodically AND their derivations have the same sing (+ or -). More...
Suppose that there is a happy bug in the center of a circular water puddle. The bug is periodically shaking its legs in order to produce disturbances that travel through the water.
If these disturbances originate at a point, then they would travel outward from that point in all directions. Since each disturbance is traveling in the same medium, they would all travel in every direction at the same speed. The pattern produced by the bug's shaking would be a series of concentric circles. These circles would reach the edges of the water puddle at the same frequency.
An observer at point A (the left edge of the puddle) would observe the disturbances to strike the puddle's edge at the same frequency that would be observed by an observer at point B (at the right edge of the puddle). In fact, the frequency at which disturbances reach the edge of the puddle would be the same as the frequency at which the bug produces the disturbances. If the bug produces disturbances at a frequency of 2 per second, then each observer would observe them approaching at a frequency of 2 per second.
What is sound wave? Sound wave is a disturbance that is transported through a medium (air, water, steel, etc.) via the mechanism of particle-to-particle interaction, a sound wave is characterized as a mechanical wave.
The generation and propagation of a sound wave is demonstrated in the animation below.
If an atom contains equal numbers of protons and electrons, the atom is described as being electrically neutral. On the other hand, if an atom has an unequal number of protons and electrons, then the atom is electrically charged (and in fact, is then referred to as an ion rather than an atom). Any particle, whether an atom, molecule or ion, that contains less electrons than protons is said to be positively charged. Conversely, any particle that contains more electrons than protons is said to be negatively charged. More...
Faraday’s law: a changing magnetic field will produce electromotive force (i.e., voltage) across a conductor.
Oersted’s law : an electric current creates a magnetic field.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 GHz to as low as 3 kHz. Like all other electromagnetic waves, they travel at the speed of light.
Does electromagnetic radiation induce current on a conductor when it interacts with the conductor? What actually happens in the microscopic level?
Yes it does and this how a wire antenna delivers currents and voltage to a receiver. Electromagnetic fields have both electric and magnetic fields components. These fields oscillate thus they have both positive and negative half-cycles. The electric fields remain outside the metal but they attract electric charges (electrons) to the surface of the metal - or repel these electrons when the field is negative. The magnetic fields induce currents in the metal's surface which are moving along the surface in direction perpendicular to the magnetic field. These charges and currents can be be calculated precisely using Maxwell's equations.
At high frequency there is a skin effect that doesn't allow fields to penetrate deep inside the conductor other than a thin skin, which gets thinner with higher frequency. For example, at 1 MHz the skin depth of copper is about 0.1mm although the wavelength is about 300m. This means that at high frequencies the fields remain outside the conductor and the conductor is just guiding the adjacent waves.
Here is a simple circuit that can be used to collect the energy in radio waves and convert the current into a DC:
For more details on above circuit, refer to https://m.youtube.com/watch?v=XpLCK88nVgU
More...The relationship of temperature in Celsius and temperature in Kelvin can be expressed in the following equation:
T(Kelvin) = T(Celsius) + 273
Fahrenheit is a thermodynamic temperature scale, where the freezing point of water is 32 degrees Fahrenheit (℉) and the boiling point 212℉ (at standard atmospheric pressure). This puts the boiling and freezing points of water exactly 180 degrees apart. Therefore, a degree on the Fahrenheit scale is 1/180 of the interval between the freezing point and the boiling point of water. Absolute zero is defined as -459.67℉.
A temperature difference of 1℉ is the equivalent of a temperature difference 0.556℃.
Fahrenheit is a thermodynamic temperature scale, where the freezing point of water is 32 degrees Fahrenheit (℉) and the boiling point 212℉ (at standard atmospheric pressure). This puts the boiling and freezing points of water exactly 180 degrees apart. Therefore, a degree on the Fahrenheit scale is 1/180 of the interval between the freezing point and the boiling point of water. Absolute zero is defined as -459.67℉.
A temperature difference of 1℉ is the equivalent of a temperature difference 0.556℃. More...
A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container. For example, in the diagram below, when you apply an extra pressure to the piston on the left, that extra pressure will be transmitted to the fluid on the right, which will push the piston on the right up. This is exactly how hydraulic system works.
In the diagram below, F1/A1 = F2/A2 More...
