Imagine making waves on a slinky. First, we make a wave with

wavelength 2 cm long, amplitude 0.2 cm, Frequency at 1 Hz and wave speed of 2 cm/s.

If we then shake the slinky twice as often, what happens to the wavelength, amplitude, frequency and wave speed?

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.

Iwould think it would be efficiency.

An electromagnet is a material in which the current produces electromagnetism and is passed to the core.  so to fill in the blanks, choices would be better if there were.an electromagnet is a magnet produced by electric current with a metal core