Electronic Principles
The core of an electromagnet is said to be in saturation when:

changing the polarity of the current in the coil changes the polarity of the magnetic field around the core
the core is permitted to move freely within the coil
an increase in current through the coil causes no further increase in the mmf
frequent changes in the direction of current through the coil causes heating effects in the core material
None of these

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Electronic Principles
The rms value of a sine waveform is:

equal to 0.707 times the peak amplitude
the time required to complete one full cycle
None of these
the number of cycles completed in one second
equal to 1.41 times the peak amplitude

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