Figure 1 shows a simplified structure of an N-channel enhancement mode MOSFET - AQA - A-Level Physics - Question 1 - 2021 - Paper 8

The terminal of the MOSFET that is connected directly to 0 V when used as a simple switch is the source.

To determine the minimum value of $V_{GS}$ needed for the lamp to operate at full power:

1. We start by calculating the current using the power formula: $P = I^2 R$ Rearranging gives: I = rac{P}{R} = rac{0.65}{154} \approx 0.00422 \text{ A}

2. Next, we can observe from the graph in Figure 2 that at $V_{GS} = 3.4 ext{ V}$, the corresponding $I_{DS}$ value is close to 4.22 mA, sufficient for the lamp's operation. Therefore, the minimum $V_{GS} = 3.4 ext{ V}$.

To analyze the CPU specifications:

1. Current consumption on stand-by: The number of transistors is $8.5 \times 10^9$. If each transistor consumes approximately 10 nA: $I_{total} = 10 nA \times (8.5 \times 10^9) \approx 85 ext{ mA}$ This indicates a significant draw even when idle, impacting energy efficiency.

2. Battery life calculation: Given the battery capacity is 3110 mAh, and with 1 A providing approximately 3600 C: $ext{Battery life} \approx \frac{3600 C}{85 mA} \approx 42.35 \text{ hours}$ The calculations imply the phone has more than enough capacity for a day's use.

3. Conclusion: The data suggests that while the CPU performs complex processes, it maintains optimal power efficiency with limited current draw, aiding battery conservation.