Recent content by aalnaif

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    Effects of lengths of solenoids

    Hello, In the design of electromagnets, why does the length of the solenoid matter? The magnetic field inside a solenoid, given by B = \mu n I , depends only on n, the number of turns per unit length, and not on the length itself. I know that the equation above applies only to the case...
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    High-frequency (inaudible by humans) acoustic noise from stepper motor

    MRFMengineer, AlephZero, Thanks for your help. Both of your posts were enlightening.
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    High-frequency (inaudible by humans) acoustic noise from stepper motor

    Hello, I am using stepper motors for some neuroscience experiments on rats. The problem is that our experiments are being corrupted by high-frequency noise. The acoustic frequency of the noise is high enough that humans can't hear it, but rats can (humans can hear up to 20 kHz, whereas rats...
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    Coulomb Potential Energy - discrepancy between like and opposite charges

    The Coulomb potential energy between two point charges is defined as: V=[(q_1)(q_2)]/[(k*r)] Suppose that you have two equal, like charges at a distance L, then V_like=q2/(k*L) Similarly, for two equal, opposite charges, V_opp=-q2/(k*L)=-V_like Both situations experience a force of...
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    Definition of electric current

    I'm confused by the definition of electric current. It is commonly defined as the time rate of change of charge (I=dQ/dt). However, considering a wire with a steady flow of electrons (a constant, non-zero current), wouldn't the number of charges entering a certain section of the wire equal the...
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    Energy discrepencies depending on frame of reference

    The other day, I was arguing that a car traveling 70mph rear-ending a car traveling 55mph is the same as a car traveling 15mph rear-ending a stationary car. My argument was that, from the frame of reference of the car that was traveling 55mph, the energy of the other car is k(152), where k =...
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