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d3nat
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Homework Statement
The news just announced that aliens armed with either electron- or proton-guns have invaded the city. A quick glance reveals that there is indeed an alien on the street just below my top-floor, north-facing window. When the alien shoots his rifle vertically at the sky, the needle of the compass I keep on the window ledge points to the left. Which of the two kinds of gun is the alien using? (Explain your answer, if you like with the help of a sketch).
Homework Equations
The Attempt at a Solution
I have this sketched on paper, but I'll just describe it because I can't attach.
I have a square notated N E S W.
In the middle, I have a circle with a dot to signify that the gun is pointing up.
According to the right hand rule, my magnetic field is rotating counterclockwise.
A compass always points in the direction of a magnetic field.
And if I'm correct, doesn't positive electric charge produce a magnetic field which is orientated at a right angle to charges direction of motion.
So it should be a protongun?