You are lost in the woods!  But you happen to have a magnetic field sensor with you.  This sensor will tell you the direction of the Earth's magnetic field where you are.  This is NOT a compass, but an actual device for measuring magnetic field.  You know that you need to travel North (geographically) to reach the nearest town. Your sensor tells you that the magnetic field is pointing to your right. Which direction should you travel in order to go to the geographic North?  Make sure to think about directions of magnetic field vs. the geographic directions.

You are assigned the job of building a very sensitive magnetic scale. Objects are hung from a horizontal rod through which an electric current is directed from left to right. The rod is loosely attached to a pair of vertical rails that allow it to slide up and down with almost no resistance. The entire scale is placed in an external magnetic field, and the current is adjusted until the rod and object levitate, balancing the downward gravitational force with an upward magnetic force. B? 1. In which direction must the external magnetic field point in order for your scale to work? 2. What current is needed to balance the scale if the combined mass of the rod and object is 1 kg, the length of the wire is 1 meter, and the magnitude of the external magnetic field is 0.1 Tesla?

An electrocardiogram (ECG) measures electric activity of neurons in the brain. Electroencephalograms and electromyograms respectively measure similar activity over the scalp and over the skin surrounding muscle cells. Because the electrical activity of the human body varies with time, the time-varying electric fields in the body lead to the generation of magnetic fields that can then be measured. The magnetocardiogram, developed in the 1960s, was the first such device. More recently, superconducting quantum interference devices (SQUIDS) have been used for these measurements. One important application of this technique is the monitoring of the fetal heart by measuring the magnetic field produced by currents in the heart at the surface of the mother's abdomen. The fetal heart at 28 weeks gestation can be modeled as a single-loop coil 1.50 cm in diameter, oriented so that the plane of the loop is parallel to the abdominal surface of the mother, and a magnetic field of 10.0 pT is typically…

An alien from a planet in the galaxy M31 (Andromeda) has a ray gun that shoots protons at a speed of 2.0 × 10^5 m/s. Design a magnetic shield that will deflect the protons away from your body. A) Suppose that the magnetic field has horizontal direction and you want to deflect the beam through a path with radius R = 2.0 m as shown in (Figure 1). Find the field strength needed to achieve the desired deflection. The mass of a proton is 1.67× 10^−27 kg and its charge is 1.6× 10^−19 C. B) What is the direction of the magnetic field in the region defined in (Figure 1), that would cause the deflection shown for the proton beam? along the path of the proton beam into the page toward the center of the curved path out of the page C)What is the direction of the magnetic force in the region defined in (Figure 1), that would cause the deflection shown for the proton beam? along the path of the proton beam into the page toward the center of the curved path out of the page