Question 1: Define potential difference (PD) and explain its role in a circuit.

Answer: Potential difference is the work done per unit charge to move a charge between two points in a circuit. It drives current and indicates the energy transferred per coulomb of charge.

Question 2: Describe how PD differs from voltage and potential energy in an electrical context.

Answer: PD and voltage are often used interchangeably to refer to the electric potential difference between two points. Potential energy per unit charge is related but refers to the energy stored; PD indicates the energy transfer when moving charge.

Question 1: A nanoscale circuit has a current of 5 μA flowing through a component with a potential difference of 2 V. Calculate the charge transferred in 10 seconds.

Answer: Charge Q = I × t = 5 × 10⁻⁶ A × 10 s = 5 × 10⁻⁵ C

Question 2: A nanodevice operates at a PD of 1.5 V and allows a current of 20 μA. How much energy is transferred in 60 seconds?

Answer: Energy = V × Q = V × I × t = 1.5 V × (20 × 10⁻⁶ A × 60 s) = 1.5 × 1.2 × 10⁻³ J = 1.8 × 10⁻³ J

Question 1: Outline the key variables that must be controlled when measuring PD across a nanoscale device.

Answer: Variables include the applied voltage, current, temperature, material properties, and environmental factors such as humidity and electromagnetic interference.

Question 2: Describe the safety precautions that should be considered when working with nanotechnology circuits involving PD measurements.

Answer: Precautions include avoiding exposure to hazardous nanomaterials, using proper shielding against electromagnetic interference, ensuring correct grounding, and following laboratory safety protocols.

Question 1: A nanowire device shows a PD of 0.8 V when a current of 10 μA is passed through it. Explain what this indicates about the energy transfer and potential for electronic applications.

Answer: The PD of 0.8 V indicates that each coulomb of charge gains 0.8 joules of energy as it moves through the nanowire. This energy transfer reflects the device's efficiency in conducting electricity, relevant for applications like nanoscale sensors or transistors.

Question 1: Explain how potential difference (PD) influences the operation of nanotechnology devices, such as nano- transistors or sensors. (6 marks)

Answer: Potential difference provides the driving force for current flow in nanodevices. In nano-transistors, PD controls the switching behaviour by modulating charge flow at the nanoscale, enabling miniaturisation and high-speed operation. In sensors, PD affects the sensitivity and response time by influencing charge transfer processes. Proper PD levels are essential for optimal device performance, energy efficiency, and reliability at the nanoscale.

Question 1: Discuss how controlling PD at the nanoscale can improve the performance of nanoelectronic devices used in medical sensors.

Answer: Precise control of PD allows for accurate regulation of charge flow, leading to higher sensitivity and lower power consumption in nanoelectronic sensors. This improves the detection of biological signals, enabling early diagnosis and real-time health monitoring.