Physics – 4.3.1 Circuit diagrams and circuit components | e-Consult

(a) The resistor limits the current flowing through the LED. Without a resistor, the LED would draw excessive current, which would likely damage or destroy it. The resistor ensures that the current remains within a safe operating range for the LED.

(b) We can use Ohm's Law (V = IR) to calculate the required resistance. First, we need to find the voltage across the resistor. The supply voltage is 9V and the LED drops 2V, so the resistor must drop 9V - 2V = 7V. We want the current through the LED to be 10mA (0.01A). Therefore, R = V/I = 7V / 0.01A = 700Ω. The required resistance is 700Ω.

(c) If the value of the resistor is increased, the current through the LED will be reduced. This will result in a dimmer LED because the amount of electrical energy flowing through the LED is less. The brightness of an LED is directly related to the current flowing through it.