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Name: Paul
Status: student
Grade: 9-12
Location: CA
Country: N/A
Date: 8/2/2005


Question:
Can an electromagnetic wave be deflected by a magnetic field? An electric field? A gravitational field?


Replies:
Paul,

I am not sure about electric and magnetic fields. I do know for a fact that E-M waves are turned by gravitational fields. An often quoted example is an observation made during an eclipse. A star was almost directly behind the sun. An image of that star appeared on both sides of the sun at the same time. The light, the E-M waves, from the star were being turned by the gravitational field of the sun.

Gravity turns light just as it turns all other things. This forms the basis for Einstein's GENERAL relativity. You cannot tell the difference between the effects of gravitational force and the effects of acceleration: In an elevator moving at a constant velocity, you, and everything else in the elevator, are pulled downward by gravity. Only the force of the floor keeps you from falling to the ground.

Turn off gravity and accelerate the elevator upward at the appropriate rate (9.8m/s^2 on Earth). You will observe EXACTLY the same thing. Objects, and E-M waves, accelerate toward the floor just as before. The floor pushes against your feet just as before. Unless the elevator has a window, you cannot tell the difference. Gravity affects everything exactly the same.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College


The short answer to all three questions is Yes. In the case of the gravitational field the deflection of light from the planet Mercury by the Sun's gravitational field is the "classic" example although gravitational lensing of distant galaxies has been observed many times since that early.

The interaction of electromagnetic waves and magnetic and electric fields is governed by Maxwell's equations. A detailed explanation of that is too long and complicated for a format like NEWTON. You might start with this web site:

http://www.absoluteastronomy.com/encyclopedia/e/el/ electromagnetic_field.htm

Vince Calder



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