What Is the Correct Resistance for Optimal LED Operation?

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To achieve optimal LED operation, the correct resistance for Rl must account for the total current drawn by all LEDs. Each LED requires 20mA, and with three LEDs in parallel, the total current is 60mA. The voltage across Rl is 7V, calculated from the supply voltage minus the LED forward voltage. Using Ohm's Law, the resistance Rl should be 7V divided by 0.06A, resulting in a resistance of approximately 116.67 ohms. Proper understanding of current distribution in parallel circuits is crucial for accurate calculations.
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Homework Statement


All LEDs in the following circuit are identical. Each LED has a switch on voltage of 2V and draws a current of 20mA for optimal light production.

Determine the resistance of Rl that gives optimum operation for all LEDs.


Homework Equations


Ohms Law V=IR


The Attempt at a Solution


becuase the LEDs are connected in parallel I calculated the voltage for Rl to be 9-2 =7V then divided that by 20mA which gave me 350ohms, which is incorrect.
 

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Each LED draws 20 mA current. There are three LEDs. So the total current drawn from the battery is...?
 


OMG I am an idiot, I didn't read the question properly, I thought the 20mA was divided amongst the 3 LEDs. Haha, anyway Thankyou!
 

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