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10 Points A beam of electrons passes undeflected through two mutually perpendicular electric and magnetic fields.  If the electric field is cut off and the same magnetic field is maintained, the electrons move in the magnetic field in a circular path of radius 1.14 cm.  Determine the ratio of the electronic charge to mass if E = 8 kV/m and the magnetic field has a flux density 2 x 10-3 T.

10 Points The diagram shows the cross section of a long metal rod of radius R = 30 mm.  The rod carries a current I = 5 kA direction out of the paper.  Find B at point P (r = 20 mm) and at the surface of the rod, assuming the permeability of the metal may be approximated as μo.  

10 Points The capacitance of an air filled parallel plate capacitor is 2.5μF. When it is half filled with a dielectric as shown in the figure, its capacitance becomes 5μF.  Determine the dielectric constant of the material.  

15 Points Two straight conducting rails form a right angle.  A conducting bar in contact with the rails starts at the vertex at t = 0 and moves with a constant velocity v = 5.2 m/s along them.  A magnetic field with B = 0.35 T is directed out of the page.  Calculate: the flux through the triangle formed by the rail at t = 3.0 s the emf around the triangle at that time. The direction of the current flow (Clockwise / Counterclockwise)

10 Points In the following RC circuit, the total resistance is 20k and the battery’s emf is 12 V. Suppose the time constant of this RC circuit is 18 μs. Find:(a) The capacitance of the circuit.(b) The time it takes the voltage across the resistor to reach 9 V after closing the switch.

15 Points If the value of Resistor R1 = 0.75 Ω, determine the current in each branch of the circuit

15 Points In the diagram, the bar AC has a mass of 50 g.  It slides freely on the metal strips 40 cm apart at the edges of the incline.  A current I flows through these strips and the bar, as indicated.  There is a magnetic field By = 0.20 T directed in the -y direction.  How large must I be if the rod is to remain motionless.  (Neglect the slight overhang of the rod)  

The modular arithmetic/remainder of 29 mod 4 is          .

In cryptography, the key take-home message of the birthday phenomenon is to         when collisions matter.

If we assume that the encryption of ‘PLAINTEXT’ with a Caesar cipher is ‘WSHPUALEA’, what key is used in the encryption?