AA = (AX Ах (a) O increasing RHR-2 в Application of Lenz's law RHR-1 R #E Equivalent circuit (b) Figure 23.11 (a) A motional emf = Btv is induced between the rails when this rod moves to the right in the uniform magnetic field. The magnetic field B is into the page, perpendiculer to the moving rod and rails and, hence, to the area enclosed by them. (b) Lenz's law gives the directions of the induced field and current, and the polarity of the induced emf. Since the flux is increasing, the induced field is in the opposite direction, or out of the page. RHR-2 gives the current direction shown, and the polarity of the rod will drive such a current. RHR-1 also indicates the same polarity for the rod. (Note that the script E symbol used in the equivalent circuit at the bottom of part (b) represents emf.)

The figure below shows a top view of a bar that can slide on two frictionless rails. The resistor is R = 5.60 0, and a 2.50-T magnetic field is directed perpendicularly downward, into the page. Let { = 1.20 m. Bin R app (a) Calculate the applied force required to move the bar to the right at a constant speed of 2.30 m/s. N (to the right) (b) At what rate is energy delivered to the resistor? W

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

A Copper bar is sliding down the rails in an applied constant magnetic field as shown in the figure below. The copper bar is sliding down the rails with a net constant velocity of 10 m/s. The rails do not have any friction (i)If the current induced in the 1000Ω resistance is 50 mA then what is the magnitude of the applied Magnetic Field. (ii)Which direction will the current flow in the resistance (A to B or B to A). Explain the reasoning