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Figure 1 shows a simplified structure of an N-channel enhancement mode MOSFET - AQA - A-Level Physics - Question 1 - 2021 - Paper 8
Question 1
Figure 1 shows a simplified structure of an N-channel enhancement mode MOSFET. State the name of the part shown in this MOSFET structure that causes the input resis... show full transcript
Worked Solution & Example Answer:Figure 1 shows a simplified structure of an N-channel enhancement mode MOSFET - AQA - A-Level Physics - Question 1 - 2021 - Paper 8
Step 1
State the name of the part shown in this MOSFET structure that causes the input resistance to be very large.
Answer
The part that causes the input resistance to be very large is the silicon dioxide layer. This layer acts as an insulator and prevents current from flowing between the gate and the channel, allowing the MOSFET to maintain a high input impedance.
Step 2
Step 3
Deduce the minimum value of V_GS needed for the lamp to operate at full power.
Answer
To find the minimum value of V_GS, we first calculate the current required for the lamp. The power (P) is given by the formula:
Rearranging gives us:
I = rac{P}{R} = rac{0.65 ext{ W}}{154 ext{ Ω}} \\ = 0.00422597 ext{ A} \approx 4.23 ext{ mA}
From the graph in Figure 2, we deduce that V_GS needs to be at least 3.4 V to ensure that I_D contains enough current for the lamp.
Step 4
Discuss, using the data provided, the result.
Answer
From the data given, the phone has about transistors, allowing for complex operations. Given the battery capacity, we can calculate the current consumption using the standby time.
Using the data from Table 1, we find:
Battery life in seconds can be calculated as follows:
Therefore, we need to compute:
ext{Time} = rac{3600 ext{ C}}{3110 ext{ mA}} \approx 1.15 ext{ hours} \approx 69 ext{ minutes}
Thus, the usage and power management dynamics of the transistors greatly improve battery efficiency.