PHYS 228 Final, Fall 2005

Final Exam Physics 228 (lab) Date: 13 Jan, 2006 Time: 4.30 PM—5.45 PM Name: -------------—------—------—-------—----- Section: Monday---------—------—-- Tuesday ----------- 7 Wednesday ----- - Answer the following questions: 3 points 1- What are the units of the number displayed by the CTFM ( Universal Counter) a) in frequency Mode?------—------—- Resolution-------------—------- b) in period mode? ------------—------ Resolution-------------—------- For a 150 KHz signal, would a frequency or period measurement with the CTFM provide the greater resolution? Explain. [ in other words find uncertainty in the frequency mode and period mode and compare.] 3 points 2- a) Can you obtain a 1.99 MHz square wave signal from your ( Furction Generator)? b) Can you obtain a 5 Volts sine wave signal from your ( Function Generator) using TTL output? c) Can you obtain a triangular wave signal having a peak value of 20 volts from your ( Function Generator)? 2 points 3- Calculate the phase difference between two voltages having the same amplitude and the same frequency. SHOW THE CALCULATION 1 0.5 the answer is:----------—------—------—-------—------—----- a 2- points 4- Ifyou are asked to measure the voltage of a 35 V battery with DMM ( digital Multi-meter) with highest sensitivity. Indicate which of the following statement is true. a) Function switch on DCV, range 20 V, positive on com and negative on V/Q. b) Function switch on ACV, range 200 V, positive on V/Q and negative on com. c) Function switch on DCV, range 200 V, positive on V/Q and negative on com. d) Function switch on ACV, range 20 V, positive on V/Q and negative on com. e) Function switch on ACV, range 1000V, positive on V/Q and negative on com 4 points 5-Develop the simplest diagram to implement the given logical equation using only NAND gates XYZ + Y°Z’ +Y Z’ 5 points 6- Indicate whether the following statements are true or false: a) The screen of the oscilloscope can provide a voltage against time display-- b) The screen of the oscilloscope can provide a voltage against another c) Any phenomenon that can be converted into a voltage can be measured with an oscilloscope------- d) The screen of the oscilloscope can provide a lissajous figure if the two channels are connected to the voltage sources and the scope display is switched to X-Y mode ------ e) Output of a “NOR gate is “ONE” if all inputs are (ZERO) ----- 5 points 7 -To calculate internal resistance of the DMM in the voltage mode we used the circuit shown. Assuming that when Rm is connected, the voltage at point a and point b (relative to common) are recorded below . a RS b Rs = 1.00 MQ = 1.0.x 10°Q IMO touch Va=5.55 V contact Vb= 4.65 V Rm( 3 )DMM why the internal resistance of the voltmeter is large 5 points 8- Given the circuit below designed by a student. Which figure gives the exact output across R ? a) Figure a. f b) Figure b c) Figure c d) Figure d The output across R is 110V 10 points 9- Given a'low pass filter as shown in the figure . where C = 0.01 pF , R = 10 kQ and FG amplitude Vi, = 10 V f) Calculate Xc at frequency 100 Hz g) Give an expression for the output voltage h) Fill in the table. Express the ratio V(out) / V(in) in Decibel (dB) i) Plot the transfer ratio in dB vs log frequency. Determine the cut off frequency from your graph Frequency| Log Frequency [10 Hz 30 100 300 [1000 3000 10 kHz