Voltage dividers are everywhere in electronics - from the volume... Show more
Physics50 views·Updated Jun 3, 2026·3 pagesUnderstanding Potential Dividers in N5 Physics Electricity
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Understanding Voltage Dividers
Ever wondered why your phone's screen dims automatically? Voltage dividers are the answer! When you connect two or more resistors in series, the supply voltage doesn't just disappear - it cleverly splits across each resistor.
The key principle is simple: voltage splits based on resistance values. If you've got two identical 500 Ω resistors connected to a 12 V battery, each resistor gets exactly 6 V. Think of it like sharing a pizza equally between two equally hungry friends.
But here's where it gets interesting - when resistors have different values, the voltage split becomes unequal. A 10 kΩ resistor will grab more voltage than a 5 kΩ resistor because the greater the resistance, the greater the voltage across it. Remember: V ∝ R from Ohm's law .
Quick Check: In a voltage divider, the resistor with the highest resistance always gets the biggest share of the supply voltage!
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Calculating Voltage Splits - Method 1
When you know the supply voltage and both resistance values, you've got a straightforward formula to work with. This is probably the most common type of question you'll see in exams.
For any resistor in the circuit, use this voltage divider equation: V₂ = × Vs. The pattern is simple - put your target resistor on top of the fraction, and the total resistance on the bottom.
Let's say you've got a 12 V supply with a 3 kΩ and 6 kΩ resistor in series. The voltage across the 6 kΩ resistor would be: V = (6000/(3000 + 6000)) × 12 = 8 V. The remaining 4 V appears across the 3 kΩ resistor.
Pro Tip: Always check your answers add up to the supply voltage - it's a foolproof way to spot calculation errors!
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of 3
Calculating Voltage Splits - Method 2
Sometimes exam questions throw you a curveball by not giving you the supply voltage directly. Don't panic - there's still a way forward using the voltage ratio method.
When you know both resistances and the voltage across just one resistor, use this elegant relationship: V₁/V₂ = R₁/R₂. This formula shows that voltage ratios equal resistance ratios in series circuits.
Imagine you've got a 2 kΩ and 8 kΩ resistor in series, and you know there's 3 V across the 2 kΩ resistor. Using the ratio: 3/V₂ = 2000/8000, so V₂ = 12 V. The total supply voltage must be 15 V.
Exam Strategy: This ratio method is perfect for those tricky questions where the supply voltage is hidden - you can often work backwards to find it!
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Physics50 views·Updated Jun 3, 2026·3 pagesUnderstanding Potential Dividers in N5 Physics Electricity
Voltage dividers are everywhere in electronics - from the volume control on your headphones to the brightness sensor on your phone. Understanding how voltage splits across resistors in series circuits is crucial for A-level Physics and will help you tackle... Show more
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Understanding Voltage Dividers
Ever wondered why your phone's screen dims automatically? Voltage dividers are the answer! When you connect two or more resistors in series, the supply voltage doesn't just disappear - it cleverly splits across each resistor.
The key principle is simple: voltage splits based on resistance values. If you've got two identical 500 Ω resistors connected to a 12 V battery, each resistor gets exactly 6 V. Think of it like sharing a pizza equally between two equally hungry friends.
But here's where it gets interesting - when resistors have different values, the voltage split becomes unequal. A 10 kΩ resistor will grab more voltage than a 5 kΩ resistor because the greater the resistance, the greater the voltage across it. Remember: V ∝ R from Ohm's law .
Quick Check: In a voltage divider, the resistor with the highest resistance always gets the biggest share of the supply voltage!
2
of 3Sign up to see the content. It's free!
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Calculating Voltage Splits - Method 1
When you know the supply voltage and both resistance values, you've got a straightforward formula to work with. This is probably the most common type of question you'll see in exams.
For any resistor in the circuit, use this voltage divider equation: V₂ = × Vs. The pattern is simple - put your target resistor on top of the fraction, and the total resistance on the bottom.
Let's say you've got a 12 V supply with a 3 kΩ and 6 kΩ resistor in series. The voltage across the 6 kΩ resistor would be: V = (6000/(3000 + 6000)) × 12 = 8 V. The remaining 4 V appears across the 3 kΩ resistor.
Pro Tip: Always check your answers add up to the supply voltage - it's a foolproof way to spot calculation errors!
3
of 3Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Calculating Voltage Splits - Method 2
Sometimes exam questions throw you a curveball by not giving you the supply voltage directly. Don't panic - there's still a way forward using the voltage ratio method.
When you know both resistances and the voltage across just one resistor, use this elegant relationship: V₁/V₂ = R₁/R₂. This formula shows that voltage ratios equal resistance ratios in series circuits.
Imagine you've got a 2 kΩ and 8 kΩ resistor in series, and you know there's 3 V across the 2 kΩ resistor. Using the ratio: 3/V₂ = 2000/8000, so V₂ = 12 V. The total supply voltage must be 15 V.
Exam Strategy: This ratio method is perfect for those tricky questions where the supply voltage is hidden - you can often work backwards to find it!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: Resistor
2Most popular content in Physics
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user