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3/28/2015 AV Math Formulas flashcards | Quizlet
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AR=W / H Aspect Ratio FormulaAR is aspect ratio; W is width; His height.
A^2 + B^2 = C^2 Screen Diagonal Formula orPythagorean TheoryA=height, B=width, andC=diagonal length
Distance=Screen Width *Throw Ratio
Estimating Throw DistanceFormulaDistance from the front of thelens to the closest point on thescreen. Screen Width is the widthof the projected image. ThrowRatio is the ratio of the throwdistance to the image width.
S(H) = D / S(L) Determining Image HeightFormula S(H) is the height of theimage on the screen. D is thedistance to the farthest viewerfrom the screen. S(L) is the levelof screen detail. S(L) =4 forinspection detail, 6 for detaileduse, and 8 for general viewing.
D=S(L) * S(H) Determining the Farthest Viewerby Task FormulaD=Distance to the farthestviewer from the screen.S(H)=height of the screen.S(L)=level of screen detail. S(L) =4 for inspection detail, 6 fordetailed use, and 8 for generalviewing. Note: S(H) and D are insame measurements.
D=T(H) * 150 Determining Viewer Distance byText Height FormulaD=distance to the farthest viewerfrom the screen. T(H) = height ofthe text on the projection screen.All units must be identical.
3/28/2015 AV Math Formulas flashcards | Quizlet
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dB=20*log(D(1)/D(2)) Decibel Formula for DistancedB=change in decibels. D(1) =theoriginal or reference distance.D(2) is the new or measureddistance. If change is positive, theresult is an increase or gain. Ifnegative, the result is a decreaseor loss.
dB=20*log(V(1) /V(R)) Decibel Formula for VoltagedB=change in decibels. V(1) isnew or measured voltage. V(R) isthe original or reference voltage.If change is positive=gain ornegative=loss.
dB=10 * log(P(1) / P(2)) Decibel Formula for PowerdB=change in decibels. P(1) =new or measured powermeasurement. P(2)=original orreference power measurement.If change is positive=gain ornegative=loss.
I = V / R Current Formula (Ohm's Law)I=current, V=voltage, andR=resistance.
P=I*V Power FormulaP=power, I=current, andV=voltage
Z(T)=Z(1)+Z(2)+Z(3)...Z(N) Series Circuit ImpedanceFormulaZ(T) = total impedance of theloudspeaker circuit.Z(X)=impedance of eachloudspeaker.
Z(T)=Z(1)/N Parallel Circuit ImpedanceFormulaLoudspeakers with the SameImpedanceZ(T)=total impedance of theloudspeaker systemZ(1)=impedance of each
3/28/2015 AV Math Formulas flashcards | Quizlet
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loudspeakerN=number of loudspeakers inthe circuit
Parallel Circuit ImpedanceFormulaLoudspeakers withDifference Impedance
Z(X)=impedance of eachindividual loudspeakerZ(T)=total impedance of theloudspeaker circuit
Series/Parallel CircuitImpedance Formulas
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Heat Load Formula Total Btu=W(E)*3.4W(E)=total watts of allequipment used in the room3.4 is the conversion factor,where 1 watt of power generates3.4 Btu of heat per hour. Thisformula does not account for theheat load generated by theamplifiers.