Voltage dividers are everywhere in electronics - from the volume...
Physics50 views·Updated 3 Jul 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!
2
of 3
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 = × 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 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 3 Jul 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...
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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 = × 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!
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- Join milions of students
By signing up you accept Terms of Service and Privacy Policy
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...
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.
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