Ohm's Law
What does 'V' represent in Ohm's Law?
Voltage (measured in volts)
In a series circuit, if one component breaks, what happens to the others?
All components stop working (circuit is broken)
In a parallel circuit, if one component breaks, what happens to the others?
Others keep working (each has independent path)
On an LED, which leg is positive: long or short?
LONG leg is positive (+)
What is the formula for calculating LED resistor value?
R = (V_battery - V_LED) ÷ I
If V = 12V and R = 4Ω, calculate the current I.
I = V ÷ R = 12V ÷ 4Ω = 3A
In a series circuit, is the current the same or different through each component?
Same current through all components
In a parallel circuit, each component receives what voltage?
Same voltage as the battery (full voltage)
What happens if you connect an LED backwards (wrong polarity)?
It won't light up (current can't flow backwards through LED)
You have 9V battery and 2V red LED. What is the voltage difference?
7V (9V - 2V = 7V)
If you double the voltage and keep resistance the same, what happens to current?
Current doubles (V and I are directly proportional)
You have a 9V battery and three identical bulbs in series. Each bulb gets how much voltage?
3V each (voltage divides: 9V ÷ 3 = 3V)
True or False: In parallel, each component has its own separate path back to the battery.
TRUE - that's what makes it parallel!
Why do we NEED a resistor with an LED?
To limit current and prevent the LED from burning out
9V battery, 2V red LED, 0.02A current. What resistor is needed?
R = (9V - 2V) ÷ 0.02A = 7V ÷ 0.02A = 350Ω
A circuit has V = 9V and I = 0.03A. Calculate the resistance.
R = V ÷ I = 9V ÷ 0.03A = 300Ω
What happens to brightness if you add MORE bulbs in series?
All bulbs get dimmer (more resistance = less current)
Why are house lights wired in parallel instead of series?
So each light can work independently - turning off one doesn't affect others, and one breaking doesn't kill all lights
Red LED = 2.0V, Yellow LED = 2.1V. Which needs a bigger resistor with a 9V battery?
Yellow LED needs bigger resistor (larger voltage difference from battery)
9V battery, 3V blue LED, 0.015A current. What resistor is needed?
R = (9V - 3V) ÷ 0.015A = 6V ÷ 0.015A = 400Ω