Diagram B (will be supplied) shows a light sensor potential divider. i) what is component A? ii) what is Vs?

i) Component A - Is an LDR - Light dependent resistorii) The voltage across both resistors is 9VWe know that because the resistors are in series that the sum of the voltage across the components is the total voltage drop. Ie Vr1 + Vr2 = 9. Ohms law tells us that V = IR, and as the resistors are in series we know the currents are the same. Therefore we can work out Vr1 and Vr2, as Ir1 and Ir2 are the same we can call them I. with the equations Vr1 + Vr2 = Vt and V = IR, we can find the equation for the voltage across Resistor 2 (LDR). From here on Vr1 = V1 and Vr2 = V2V1 + V2 = VtVt = IR1 + IR2Vt = I*(R1+R2)Eq 1: I = Vt/(R1+R2)Eq 2: Vt = IR1 + V2Vt = (vt/(R1+R2))R1 + V2Vt - (Vt/(R1+R2))R1 = V2V2 = (Vt(R1+R2) - VtR1)/(R1+R2)V2 = Vt(R2/(R1+R2))

LW
Answered by Linden W. Design & Technology tutor

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