What Is the Correct Resistance for Optimal LED Operation?

[TyErd]

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

because 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.

 

[rl.bhat]

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

 

[TyErd]

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!