1. Conceptual Questions (1 pt) a) In lecture 5c (MRI) we introduced the idea of an alternating magnetic field B1. Why must the direction of the pulse B1 be alternated? At what frequency must this oscillation occur? Does this frequency depend on B1? b) Briefly explain how to use the right-hand rule in the following situations (i. e. what to do with your right hand): i. When performing the cross product �⃗ = �⃗ × �(⃗. ii. Find the direction of the magnetic field produced by a current-carrying wire. iii. Find the direction of the magnetic field, given the direction of the electrical current in a circular loop