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

The terminal connected directly to 0 V is the source.

To find the minimum value of $V_{GS}$ necessary for the lamp to operate at full power, we can utilize the power formula:

$P = I^2 R,$ where the total power $P$ is 0.65 W and the resistance $R$ is 154 Ω.

First, calculate the current:

I = rac{ ext{Power}}{ ext{Resistance}} = rac{0.65}{154} ext{ A} = 0.00423 ext{ A} ext{ (approximately)}.

From the graph, identify the $V_{GS}$ values where the current $I_{DS}$ is approximately 4.23 mA. The threshold voltage $V_{GS}$ required is approximately 3.4 V to ensure proper operation.

The CPU contains about $8.5 imes 10^9$ transistors, which allows for increased performance and efficiency in computations. Greater transistor counts enable parallel processing, allowing the CPU to handle more instructions simultaneously.

With the battery capacity of 3110 mAh, and the CPU's efficiency in terms of power usage, we can estimate the operating time. The standby current consumption (about 10 nA for an individual MOSFET) sums up to an overall energy-efficient design, allowing the mobile phone to last longer between charges.

This high number of transistors also allows for more complex tasks to be processed, making modern mobile phones capable of running sophisticated applications seamlessly.