Final answer:
The nominal R-value is the resistance specified by the manufacturer, the on-screen R-value is the resistance measured in real-time, and the effective R-value includes factors like temperature and circuit components.
Step-by-step explanation:
The nominal R-value, also known as the resistance value, is the resistance of a component or circuit element as specified by the manufacturer, and it remains constant regardless of the operating conditions.
The on-screen R-value refers to the resistance value displayed on measuring instruments, such as multimeters or oscilloscopes, when measuring the resistance of a component or circuit element in real-time.
The effective R-value takes into consideration factors such as the temperature coefficient of resistance and the impact of other components in a circuit, and it represents the actual resistance experienced by the circuit or component.
For example, let's consider a resistor with a nominal resistance of 100 ohms. When measuring the resistance with a multimeter, the on-screen R-value might display a slightly different value, like 99.9 ohms. This discrepancy accounts for factors such as the accuracy of the multimeter. However, when taking into account the impact of temperature changes or other components in the circuit, the effective R-value might be significantly different, such as 97 ohms.