# Electromagnetic radiation (light) consists of waves. More than a century ago, scientists thought that light, like other waves, required a medium (called the ether) to support its transmission. Glass, having a typical mass density of ñ = 2690 kg/m3, also supports the transmission of light. What would the elastic modulus of glass have to be to support the transmission of light waves at a speed of v = 2.27 · 10^8m/s? (For comparison: the actual elastic modulus of window glass is 5 · 10^10 N/m2.)

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523873

Created
April 1, 2011 1:09pm UTC

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1. The speed of a wave associated with pressure variations in a medium (such as sound waves) is

v = sqrt (E/rho)
where E is the elastic modulus and rho is the density of the medium.

In your case, solve for E, using c for the speed of light.

Light is NOT associated with pressure-variation waves. It is purely electromagnetic, does not involve mass and does not require a transmitting medium.

523877

Created
April 1, 2011 1:18pm UTC

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524020

Created
April 1, 2011 8:14pm UTC

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3. ehh malý Vsquare*density diyosun sonuç sonsuz mu çýkýcak?