(28 – 1) Chapter 28 Magnetic Fields In this chapter we will cover the following topics: Magnetic field vector Magnetic force on a moving charge Magnetic field lines Motion of a moving charge particle in a uniform magnetic field Magnetic force on a current carrying wire Magnetic torque on a wire loop Magnetic dipole, magnetic dipole moment Hall effect Cyclotron particle accelerator

What is the equivalent resistance between points F and G? Each Resistor is 8 Ω. (A) 2.5 Ω (B) 8.0 Ω (C) 2.0 Ω (D) 4.0 Ω (E) none of these

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P magnetic field line magnetic field lines P Q (28 – 6)

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hitt The current in the 5.0 Ω resistor in the circuit shown is: (1)0.42A (2) 0.67A (3) 1.5A (4) 2.4A (5) 3.0A

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Two isolated conducting spheres are separated by a large distance. Sphere 1 has a radius of R and an initial charge 2Q while sphere 2 has a radius of 3R and an initial charge 8Q. A very thin copper wire is now connected to the spheres. Charge flows between the spheres until they reach the same electrical potential. How much charge will be transferred from sphere 2 to sphere 1? (Note that the charge transferred can be positive, negative or zero.) (1) Q/2 (2) 2Q (3) –Q/3 (4) -3Q (5) None of these

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C C Top view Side view (28 – 13)

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LL L R R R (28 – 15)

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Four identical light bulbs A, B, C and D are connected in series to a constant voltage source. A wire is then connected across B. What is the brightness of A relative to its former brightness? (1) 0.44 (2) 0.56 (3) 1.78 (4) 2.25 (5) none of these Hitt