A group of equal resistors connected in series, so their equivalent resistance was 100 1 and when they connected in parallel their equivalent resistance become 42, then the value of one of them is a.20 b.25 c.100 d.125 please explain why if you can't just an answer would be fine :)

We will use a video to study faraday’s law of electromagnetic induction by analyzing the induction that occurs due a coil of copper wire sliding along an air track that passes through an external magnetic field. specifically, we will: examine some of the main principles behind faraday’s law. apply lenz’s law to determine the direction of the induced emf. take measurements of the induced emf from the voltmeter as the coil passes into and out of the external magnetic field. use the horizontal scale provided to determine the speed of the coil. calculate the magnetic field induced in the coil as it passes into and out of the external magnetic field.