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Unformatted text preview: 1 Physics 4B FINAL EXAM Chapters 22 - 34 Fall 1997 Name:_________________________________________ Posting Code _____ _____ _____ Solve the following problems in the space provided. Use the back of the page if needed. Each problem is worth 10 points. You must show your work in a logical fashion starting with the correctly applied physical principles which are on the last page. Your score will be maximized if your work is easy to follow because partial credit will be awarded. If you want your grade posted, put alphanumeric characters in the three spaces at the top right. 1. Write down Maxwell’s Equations. Name each one and explain what it means. Gauss's Law for Electricity r E • d r A ∫ = q ε o Charges creates diverging electric fields. Faraday's Law r E • d r s ∫ = - d Φ B dt Changing magnetic flux creates circulating electric fields. Gauss's Law for Magnetism r B • d r A ∫ = Their are no magnetic monopoles and magnetic fields never diverge. Ampere's Law r B • d r s = μ o ∫ dq dt +μ o ε o d Φ e dt Current or changing electric fields create circulating magnetic fields. 2. The charge q 1 =+12.0μC has a mass of 3.00g and the charge q 2 =-8.0μC has a mass of 5.00g. At some instant in time they are a distance 3.20cm apart as shown at the right. Find (a)the electric field felt by the charge q 1 , (b)the electric force on the charge q 1 , (c)the electric force on the charge q 2 and (d)sketch the directions of these vectors in the drawing at the right. (a)The field felt by q 1 is created by the point charge q 2 , E 2 = k q 2 2 r = (9.00x10 9 ) 8.00x10- 6 (0.0320) 2 ⇒ E 2 = 7.03x10 7 N/C (b)The force on q 1 can be found from the definition of electric field, F 12 = q 1 E 2 = (12.0x10- 6 )(7.03x10 7 ) ⇒ F 12 = 844N (c) The force on q 2 is equal and opposite to the force on q 1 according to Newton’s Third Law, F 21 = 844N q 1 q 2 3.20cm E 2 F 12 F 21 2 3. Find the potential due to a ring of total charge Q and radius R at the point P a distance x from the center of the ring along the axis as shown at the right....
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- Fall '09
- Work, Magnetic Field, long straight wire, amperian loop, entire amperian loop, dt dt Charges