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Voltage is observed to decrease to 80% of the value in part (a). What is the val

ID: 1338762 • Letter: V

Question

Voltage is observed to decrease to 80% of the value in part (a). What is the value of the resistance? Suppose a paper capacitor is to be constructed with a capacitance of 0.01 muF. If the thickness of the paper is 0.1 mm and its (relative) dielectric constant is 2, what area is required for each plate? Suppose a disc-ceramic capacitor is to be constructed with a capacitance of 0.01 muF- The thickness of the ceramic is 0.1 mm and its relative dielectric constant is 1000. What area is required for each plate? Suppose a 10-kOhm resistor, a 2-muF capacitor, and a switch are connected in series to a 20-V battery, as shown in Figure A1-18a. Also suppose the switch has been in position for a long time and is switched to position at t = 0. Calculate and plot the voltage across the capacitor vc for the time interval from 0 up to 3 characteristic times. Perhaps a dozen points will do. You should obtain the rising part of the charge/discharge plot in Figure A1-18c. An important integrated circuit discussed in Chapter A7 (the 555 timer) makes use of an RC charging circuit. In one connection, it performs a test on a charging capacitor, asking "When does the capacitor's voltage reach 2/3 of the charging voltage?" Thus, in the circuit pictured in Diagram A1-9, what time is required for the capacitor voltage to reach 6.00 V after switch 5 is opened? A certain voltage is characterized by the expression v = 5 V sin (0.0628 sec^-1 t) The argument of the sine function is in radians. Give the following characteristics for it: average voltage rms voltage peak voltage frequency peak-to-peak voltage period Consider the circuit pictured in Diagram A1-10. Make a moderately accurate sketch of the voltage between the terminals versus time. Write out a derivation for the effective capacitance of 3 capacitors connected in series; that is, derive Equation A1-32 for Figure A1-17. Assume that a l- muF capacitor is connected to a 6.3-Vrms, voltage. Find the rms current flowing through the capacitor if the frequency is 60 Hz, and also if it is 10 kHz. Assume a 1-mH (millinery) choice is connected instead to the 6.3-V,m, source. Find the currents for the two frequencies. Consider the transformer with the primary and secondary windings pictured in Diagram A1-11. Tap B is actually connected to the earth and is a true ground. If there are 5000 turns on the primary, what is the total number of turns in the secondary? How many windings exist between tap B and lead C? Make a sketch of the voltage (relative to ground) versus time for tap A and also for tap C. Draw the voltage from tap A as a solid line and from Assume that a resistance Rs is connected to the secondary of a transformer, that Equation Al-53 is valid for the transformer, and that the transformer is ideal; that is, all power presented to the primary of the transformer is passed to the output of the secondary. Show that the impedance Rp, presented by the primary to any ac voltage source connected to it, is given by Rp = (Np/Ns)^2 Rs where R, is the resistance connected to the secondary

Explanation / Answer

17) The peak voltage is the maximum voltage given by this function. Max. value of sin function is 1. Hence peak voltage is given by Vp= 5V.

a) average voltage = (2/pi)Vp = 0.637* 5V = 3.185V

b) peak voltage, Vp= 5V

c) peak to peak voltage = 2Vp= 2*5V = 10V

d) rms voltage = (1/sqrt(2))Vp = 0.707*5V = 3.535V

e) Frequency, f = w/2pi = where w is the angular frequency measured in radians/sec

Here 0.0628 is the angular frequency.

therefore, f = 0.0628/2*3.14 = 0.01sec-1

f) Time period, T = 2pi/w

Hence, T = 2*3.14/0.0628 = 100 seconds