An electromagnet in a physics laboratory is damaging electronic apparatus in its vicinity. You suspect that the damage is due to unusually large induced currents created each time the electromagnet power supply is turned on, so you decide to monitor the magnet's magnetic field. Figure P29.76 shows the ficld magnitude as a function of time during the first \(18 \mathrm{~s}\) after you connect the magnet to a power supply. Instead of smoothly increasing to its designed value of \(0.90 \mathrm{~T}\), the field magnitude starts to decrease after about \(3.0 \mathrm{~s}\), very likely due to fluctuations in its power supply. What is not clear is whether these fluctuations can account for the damage, because the electronic apparatus is designed with the expectation that the change in magnetic field strength will be linear with time.

Data from Figure P29.76

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1.0 0.8 B 0.6 0.4 0.2 20 (s) 2 4 6 8 10 12 14 16 18