document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=867377>Question 867377</A>: <I><SPAN STYLE=\"word-break: break-all;\"> During an experiment, the intensity i(t) of the electric current of a device as a function of time t elapsed since the beginning of the experiment is given by:		\r<BR>\n" );
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document.write( "i(t)=6sin((pi*t/12)+(2*pi/3)+6\r<BR>\n" );
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document.write( "The device emits a sound signal each time the current’s intensity is equal to 9.<BR>\n" );
document.write( "The experiment lasts 120 seconds.<BR>\n" );
document.write( "How many sound signals does the device emit during the experiment?\r<BR>\n" );
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document.write( "After trying to graph it on google, I got 6. I don't fully understand how to get it anyway but the graph way, so I'm grateful for any help.\r<BR>\n" );
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document.write( "Thanks in advance! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #523011 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=523011\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> During an experiment, the intensity i(t) of the electric current of a device as a function of time t elapsed since the beginning of the experiment is given by: <BR>\n" );
document.write( "i(t)=6sin((pi*t/12)+(2*pi/3)+6 <BR>\n" );
document.write( "The device emits a sound signal each time the current’s intensity is equal to 9.<BR>\n" );
document.write( "The experiment lasts 120 seconds.<BR>\n" );
document.write( "How many sound signals does the device emit during the experiment? <BR>\n" );
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document.write( "Period = (2pi)/(pi/12) = 24 seconds<BR>\n" );
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document.write( "Phase shift = -c/b = -[(2pi/3)/(pi/12)] = -8<BR>\n" );
document.write( "# of periods in 120 sec = 120/24 = 5<BR>\n" );
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document.write( "Since the range of \"i\" is [0,12] i will equal 9 twice during<BR>\n" );
document.write( "each cycle.<BR>\n" );
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document.write( "# of alarms = 10<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28400%2C400%2C-20%2C120%2C-10%2C20%2C6sin%28%28pi%2F12%29x+%2B+%282%2F3%29pi%29%2B6%29%2C9 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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