A student investigates a light-dependent resistor (LDR). The student assembles a series circuit consisting of a power supply, a switch, a $$\(470 \Omega\)$$ resistor and an LDR. The student covers the LDR with a piece of card and repeats the procedure described in (b) and (d). $$\[ \begin{aligned} & V_{X Y}= \\ & V_{Y Z}= \end{aligned} \]$$ Calculate the resistance $$\(R_{\mathrm{D}}\)$$ of the LDR in the dark using the equation: $$\[ R_{\mathrm{D}}=\frac{470 \Omega \times V_{\mathrm{YZ}}}{V_{\mathrm{XY}}} \]$$ $$\[ R_{\mathrm{D}}= \]$$ $$\(\Omega\)$$ (ii) The student removes the card from the top of the LDR and slowly lifts it vertically upwards away from the LDR until the card is 30 cm above the LDR. The student observes and records the readings on the voltmeter across the LDR ( $$\(V_{\mathrm{YZ}}\)$$ ) as the card is raised. Table 2.1 shows the student's results. Table 2.1 Describe how the p.d. across the LDR ( $$\(V_{Y Z}\)$$ ) changes as the distance between the card and the LDR increases. . .

Answer:

Knowledge points:

Solution: