Instructions: Answer all short answer questions and 3 of the 4 lettered problems
ID: 1507432 • Letter: I
Question
Instructions: Answer all short answer questions and 3 of the 4 lettered problems. This is intended to be 1/2 of the final in length and difficult If you are able to answer the questions you should be OK on the final. No representation is made that the same questions will appear on the final. Answers must give correct units and be reasonable as to accuracy. You have been provided a box of 3muF precision capacitors. What is the smallest number of capacitors needed for a circuit of 4.5 mu F._______ A typical nucleus is 10^minus l5 m in radius, what potential difference must a proton be sent through to approach within this distance of a gold nucleus (Z=79)? A conducting wire is drawn to 4 times its length and one half its radius. By what factor is its resistance increased? A new type of electrochemical cell has an emf of 1.567 volts when measured at zero current and a terminal voltage of 1.500 volts when 250 mA flows through it. What is the internal resistance of the cell? The magnetic North pole of the earth is on the earth primes rotation axis is due to buried permanent magnets moves around a bit from year to year. The magnetic flux through a loop will be maximal if the magnetic field is perpendicular to the axis of the loop along the axis of the loop. The reactance of a capacitor goes down with frequency, Consider an LRC series circuit If L is reduced by a factor of 2 and c is increased by a factor of 8, by what factor does the resonant frequency increase? A transformer used with Neon signs may have 100 turns for its primary and 40,000 turns for its secondary coil. If a 110 rms voltage is applied to its primary coil what will the rms output of the secondary? If the primary coil of a transformer is connected by mistake to a dc source, what will happen? nothing excessive current will flow in the primary, possibly burning it out excessive current will flow in the secondary.Explanation / Answer
1. two capacitor are connected in series. then equivalent will be
1/C' = 1/3 + 1/3
C' = 1.5 uF
now connect two capacitors in parallel.
Ceq = C + C' = 3 + 1.5 = 4.5 uF
Ans. 3 (Three capacitors)
2. PE when proton at nucleus.
PE = kq1q2/r
= ( 9 x 10^9 x 79 x 1.6 x 10^-19 x 1.6 x 10^-19) / (10^-15)
PE = 1.82 x 10^-11 J
Using energy conservation,
PE + KE = constant
0 + K = 1.82 x10^-11 + 0
K = 1.82 x 10^-11 J
and K = q deltaV
1.82 x 10^-11 = (1.6 x 10^-19) deltaV
deltaV = 113.76 x 10^6 eV = 113.76 MeV