With the iron core inserted inductance goes up to 12.5 mH. The time constant is L/R so the time constant increases.
The stranded core made up of many insulated rods reduces Eddy currents and has the higher inductance. The stranded rod is 56.5 mH and the solid iron core is 12.5 mH.
Oscilloscope settings and wiring. To get the channels in phase the external switch must be on and the synch connected to channel 1 positive.
The function generator is set to a square wave of 797.3 Hz.
RL and RC time constants are sometimes set up together. They share a common oscilloscope. This is the RL set up.
RL and RC time constants are sometimes set up together. They share a common oscilloscope. This is the RC set up 5F30.20C.