Open circuit
A gap in the wire or switch stops the loop, so current becomes zero.
Current & Voltage Course
Lesson 7 of 16: Open vs Closed Circuit
Move step by step through the course and keep track of where you are.
Simulation
Open Circuit vs Closed Circuit
A circuit works only when the electrical path is complete. If the path breaks, current stops right away.
Circuit State
Closed
Voltage
9.0 V
Current
1.50 A
Core idea
A closed circuit has a complete path, so current can flow from the battery through the components and back again.
Simple idea
Closed path means current can move. Open path means current stops.
Circuit View
Watch the circuit path respond
Closed circuit completes the loop. Open circuit breaks the path and stops current.
Path View
Watch the path open and close
This simulation shows one important rule very clearly: current only moves when the loop is complete from the battery, through the load, and back again.
Path status
Complete
A complete path lets current travel through the circuit.
Current result
1.50 A
Open circuit gives zero current. Closed circuit allows flow.
Circuit effect
LED On
The load works only when the path is closed.
What to notice
Voltage and resistance still matter, but first the circuit needs a complete path. Without that path, current stays at zero no matter what values you set.
Beginner Summary
Keep the path idea in mind
This lesson becomes easy when you remember one picture: current can move only when the electrical path is complete from the battery, through the load, and back again.
Open circuit means a break in the path. Closed circuit means the loop is complete and ready to carry current.
Closed circuit
A complete loop lets current pass through the components and back to the source.
Why it matters
Switches, buttons, and relays work by opening or closing the path.