How does this potential divider circuit work?

Click For Summary
Changing the resistance of a variable resistor in a potential divider circuit affects the current, which subsequently alters the voltage across the other resistor. The total voltage remains constant, but the ratio of voltages across the resistors changes based on the resistance values. When the variable resistor is reduced to zero, it creates a scenario where all voltage is dropped across the other resistor. This demonstrates the principle of voltage division, confirming that option (B) is correct. Understanding these relationships is crucial for analyzing potential divider circuits.
Dr. Who
Messages
9
Reaction score
0
Homework Statement
Below is an MCQ that appeared in a GCSE exam. I am confused about the solution. Please guide.
Relevant Equations
I= V/R (Ohm's Law)
Screenshot_20240226-063918~2.png

Screenshot_20240226-063948~2.png

The correct option is supposed to be (B). Can someone please explain why changing the resistance of the variable resistor affects the voltage across the other resistor? Also explain why (B) is the correct option? Thanks
 
Physics news on Phys.org
changing the resistance changes the current through the circuit, which in turn changes the voltages across the resistors. The TOTAL voltage across the two can't change but the ratio clearly changes. Think in extremes. What happens if the variable resistor is taken all the way to zero?
 
Thread 'Chain falling out of a horizontal tube onto a table'

Thread 'Chain falling out of a horizontal tube onto a table'

My attempt: Initial total M.E = PE of hanging part + PE of part of chain in the tube. I've considered the table as to be at zero of PE. PE of hanging part = ##\frac{1}{2} \frac{m}{l}gh^{2}##. PE of part in the tube = ##\frac{m}{l}(l - h)gh##. Final ME = ##\frac{1}{2}\frac{m}{l}gh^{2}## + ##\frac{1}{2}\frac{m}{l}hv^{2}##. Since Initial ME = Final ME. Therefore, ##\frac{1}{2}\frac{m}{l}hv^{2}## = ##\frac{m}{l}(l-h)gh##. Solving this gives: ## v = \sqrt{2g(l-h)}##. But the answer in the book...
View full post »

Similar threads

Understanding example in Wikipedia entry for open circuit voltage
  • · Replies 3 ·
Replies
3
Views
2K
Circuit with potential difference across battery being zero?
  • · Replies 3 ·
Replies
3
Views
1K
Ohm's Law - Finding Source Voltage
  • · Replies 3 ·
Replies
3
Views
2K
Finding Optimal Fixed Resistor for Potential Divider Circuit
  • · Replies 45 ·
2
Replies
45
Views
4K
Can a reed switch use a wheatstone bridge/potential divider?
  • · Replies 1 ·
Replies
1
Views
2K
Electric Potential Energy of Point Charge Systems
  • · Replies 2 ·
Replies
2
Views
1K
Finding an open-cicuit voltage, why is resistor in series ignored?
  • · Replies 2 ·
Replies
2
Views
1K
Write boolean expression describing this circuit
  • · Replies 4 ·
Replies
4
Views
1K
Why do the headlights on the car become dim when the car is starting?
  • · Replies 4 ·
Replies
4
Views
2K
Sign conventions for Kirchhoff's loop rule
  • · Replies 7 ·
Replies
7
Views
2K