What is Electromagentic: Definition and 60 Discussions

The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.
The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end. The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications. The limit for long wavelengths is the size of the universe itself, while it is thought that the short wavelength limit is in the vicinity of the Planck length. Gamma rays, X-rays, and high ultraviolet are classified as ionizing radiation as their photons have enough energy to ionize atoms, causing chemical reactions.
In most of the frequency bands above, a technique called spectroscopy can be used to physically separate waves of different frequencies, producing a spectrum showing the constituent frequencies. Spectroscopy is used to study the interactions of electromagnetic waves with matter. Other technological uses are described under electromagnetic radiation.

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  1. P

    Charge on q from other charges given net force is zero

    Homework Statement Consider the figure below, we need to find the charge on Q_0, both charges Q are negative. It is given that the net charge on Q_A is zero. The figure of the problem is attached. The Attempt at a Solution I understand how to get the solution except for one part. I'm just...
  2. P

    Design 1.5 A Solenoid & Charge 1.5 V Battery

    Hey All, I'm trying to design a solenoid that would generate about minimum 1.6 A of current in order for me to charge up a 1.5 A 1.5 V battery. I already designed one which is about 10CM in length and unknown number of turns (as I used a drill to wind the coils around it. so I would guess its...
  3. Aavatar

    Magnetic Field of a rotating Cylinder

    Homework Statement .[/B] Given an infinitely long charged metal cylinder that is rotating with an angular velocity ##\omega## The charge density per unit length is ##\rho##. Find the magnetic field within the cylinder. I'm trying to solve this problem by using Ampere's Law. But couldn't reach...
  4. KronosZ

    Conservation of Energy and current

    Assume there is a table with an infinite long wire passing through the centre and few iron pieces lying around the wire on the table. Now I pass current through the wire which creates electro magnetic field due to which all the iron particles get magnetic potential energy. They are attracted...
  5. U

    Ib extended essay about magnetic repulsion (maglev trains)

    I have been trying to come up with a good question for my Ib extended essay which is a 4000 words essay about any physics topic of my choice. However, with this topic I need to come up with an experiment to further investigate this topic and write up an analysis and conclusion. I am really...
  6. A

    Using Red Light to Reduce Effect of Ambient Light

    Hello, I have heard many times that red lighting is good for imaging applications where the effect of ambient light needs to be reduced to a minimum. What is the theory behind this? Why does red light (vs. other colors) reduce the effect of ambient light? Thank you.
  7. Jon Mel

    Gravitational Effect of Electromagnetic Radiation

    Hello PPer's, I have been considering the effect to which electromagnetic radiation emitted from stars might play in the gravitational coalescence of galaxies. Surrounding every galaxy there must be a halo of electromagnetic radiation streaming outwards at the speed of light which diminishes...
  8. D

    Electromagentic Induction Sinusoidal Wave Help

    When you have a magnet moving up and down a coil. The magnet cuts the field lines. Which generates an AC current in the coil. In my exam, there was a sinusoidal curve showing the generation of AC current. When the curve crossed the x-axis, that point was labelled X. Now at that point was the...
  9. N

    Electromagentic brake for AC motor

    Hi, I want to create a electromagentic brake for AC motor. could you let me know how can I calculate wire lengh and what is the gauge of wire. if you have any calculating table please let me know. Regards, Naveen
  10. N

    Electromagentic Field vs. Gravity Field

    I read somewhere that at small atomic levels (quantum levels) the electric force is some 100,000 stronger than the force of gravity. But long range (hundred of millions of miles to light years), gravity is the dominant force holding objects together or close by. Why is this? Could it...
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