This layer of the atmosphere is a fairly good conductor, and radio waves are often "bounced" off the bottom of the ionosphere back toward the earth, in a process called skip or skywave propagation. Due to these properties, the space between the surface of the ea and the bottom of the ionosphere acts like a closed wave guide that will exhibit resonance for very low frequencies. Resonance excitations in the cavity are caused by lightning strikes, which hit the earth about 50 to 100 times a second. These low atmospheric resonance frequencies are known as Schumann resonances, named after the physicist Winfried Otto Schumann, who first calculated them in 1952. There are several Schumann frequencies that occur in the low frequency background, which ranges from 3 to 60 Hz. highest intensity resonance mode (called the fundamental) occurs at 7.83 Hz. Other Schumann resonances occur at 14.3, 20.8, 27.3. and 33.8 Hz. Around 20 years ago, research showed that the majority of biological systems exhibit electrical activity in the same ran as the Schumann resonances. New theoretical work suggests that primordial cells synchronized their electrical activity to the natura atmospheric resonances, and this evolutionary process is evident today across a gigantic scale-from single-celled organisms to the electrical activity in our brains. The surface of the earth and the bottom of the ionosphere act like a giant capacitor, and we can mode one path that stretches between them as a circuit consisting of a resistor and capacitor connected in series. Assume the atmosphere has an average resistance of 2.00 x 1020, and the capacitance is equal to 0.070 F. (a) What is the capacitive reactance of the circuit when it is active at the fundamental Schumann resonance frequency? (b) What is the impedance of this circuit? (c) What is the rms value of the current in the circuit, if the maximum voltage is 3.50 x 105 V? (a) Number (b) Number (c) Number i 322.8 2.36e5 1.49 Units D Units D Units A
Properties of sound
A sound wave is a mechanical wave (or mechanical vibration) that transit through media such as gas (air), liquid (water), and solid (wood).
Quality Of Sound
A sound or a sound wave is defined as the energy produced due to the vibrations of particles in a medium. When any medium produces a disturbance or vibrations, it causes a movement in the air particles which produces sound waves. Molecules in the air vibrate about a certain average position and create compressions and rarefactions. This is called pitch which is defined as the frequency of sound. The frequency is defined as the number of oscillations in pressure per second.
Categories of Sound Wave
People perceive sound in different ways, like a medico student takes sound as vibration produced by objects reaching the human eardrum. A physicist perceives sound as vibration produced by an object, which produces disturbances in nearby air molecules that travel further. Both of them describe it as vibration generated by an object, the difference is one talks about how it is received and other deals with how it travels and propagates across various mediums.
Trending now
This is a popular solution!
Step by step
Solved in 2 steps with 1 images