When you swipe a credit card, the machine sometimes failsto read the card. What can you do differently?(a) Swipe the card more slowly so that the reader has moretime to read the magnetic stripe.(b) Swipe the card more quickly so that the induced emf ishigher.(c) Swipe the card more quickly so that the induced currentsare reduced.(d) Swipe the card more slowly so that the magnetic fieldsdon’t change so fast.

An airplane heads north of east by 18 degrees for a distance of 67km then heads north for 39km. What is the planes total displacement?

An MRI technician moves his hand from a region of very low magnetic field strength into an MRI scanner’s 2.3 T field with his fingers pointing in the direction of the field. (a) Find the average emf induced in his wedding ring, given its diameter is 2 cm and assuming it takes 0.29 s to move it into the field.

A copper ring and a gold ring of the same dimensions are placed in magnetic fields so that there is the same change in magnetic flux through them. Compare the induced electric fields and currents in the rings.

The earth’s magnetic field points toward(magnetic) north. For simplicity, assume that the field has no vertical component (as is the case nearthe earth’s equator). How should you hold it to get zero emf as you walk toward the east? (i) East-west; (ii) north-south; (iii) up-down; (iv) none of these.

A 2 meter-long bar is being moved to the right at a constant speed. The bar is sliding on aframe that includes a resistor with R = 3.25 Ω. There is also a uniform 5.75-T magneticfield, directed into the page. At what speed should the bar be moved to produce a currentof 0.800 A in the resistor

An airplane flies level to the ground towardthe north pole. (a) Is the induced emf from wing tip to wing tipwhen the plane is at the equator greater than, less than, or equalto the wing-tip-to-wing-tip emf when it is at the latitude of NewYork? (b) Choose the best explanation from among the following:I. The induced emf is the same because the strength of theEarth’s magnetic field is the same at the equator and at NewYork.II. The induced emf is greater at New York because the verticalcomponent of the Earth’s magnetic field is greater there thanat the equator.III. The induced emf is less at New York because at the equator theplane is flying parallel to the magnetic field lines