Simple LED circuit - basic electronics

The video tutorial explains how to calculate the appropriate resistor for connecting LEDs to a power supply. It covers the calculation of resistance needed for both red and yellow LEDs, considering their voltage drops and current requirements. The tutorial also discusses choosing the correct resistor power rating and estimating battery life for the circuit. Practical examples are provided, including handling situations where the exact resistor value is unavailable.

What is the required resistance for a red LED with a 3-volt supply and a 2-volt drop, needing 20 milliamps of current?

• 100 ohms

• 50 ohms

• 200 ohms

• 10 ohms

If you have a 9-volt battery and a yellow LED with a 2-volt drop, what is the voltage drop across the resistor?

• 7 volts

• 5 volts

• 2 volts

• 9 volts

Which resistor should be chosen to ensure the LED's longevity when the options are 330 ohms and 390 ohms?

• 390 ohms

• 350 ohms

• 300 ohms

• 330 ohms

How do you calculate the power rating for a resistor in a circuit?

• Voltage divided by current

• Current squared multiplied by resistance

• Resistance divided by current

• Voltage multiplied by resistance

If a battery is rated for 500 milliamp hours, how long will it power a circuit drawing 18 milliamps?

• 27 hours

• 500 hours

• 50 hours

• 18 hours