When 120 V is applied across a 20 m long wire, the magnitude of the current density was found to be 2 * 10 ^ 8 * A / (m ^ 2) . The resistivity of this wire is

What is the single most important equation in all of physics?

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.

Suppose astronomers built a 140-meter telescope. how much greater would its light-collecting area be than that of the 10-meter keck telescope? express your answer using two sign