======Ohm's Law======


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**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Voltage, Current, and Resistance Relationship
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====Summary====                   
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====Procedure====  
  - Gather equipment: a low-voltage DC power supply, a fixed resistor (e.g., 100 Ω), a voltmeter, an ammeter, and connecting leads.
  - Connect the resistor in series with the ammeter, and place the voltmeter across the resistor.
  - Switch on the power supply at a low voltage (e.g., 1 V). Record the current from the ammeter and the voltage from the voltmeter.
  - Increase the voltage step by step (e.g., in 1 V increments), recording the corresponding current at each step.
  - Plot a graph of voltage (y-axis) against current (x-axis). A straight line through the origin indicates ohmic behavior, with the slope equal to the resistance.
  - Repeat with different resistors to compare resistance values.



====Links==== 
Ohm's Law I - TeachEngineering:
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Ohm's Law with practical demonstration - Kitronik: 
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📄 Ohm's Law I - ncwit.org: [[https://www.teachengineering.org/activities/view/ohm1_act_joy]]\\

====Variations====
  * Try with a variable resistor to show how changing resistance affects the current at a fixed voltage.



====Safety Precautions====
  * Use a low-voltage DC power supply (typically under 12 V) to avoid electric shock.
  * Do not exceed the power rating of the resistor to prevent overheating.
  * Switch off the supply before changing connections.
  * Allow bulbs or resistors to cool before handling if they become hot.




====Questions to Consider====
  * What does the gradient of the voltage-current graph represent? (The resistance of the component.)
  * Why does a straight-line graph through the origin indicate ohmic behavior? (Because voltage is directly proportional to current.)
  * How does the graph for a filament bulb differ from a fixed resistor, and why? (It curves because resistance increases as the filament gets hotter.)
  * What happens to current if voltage is doubled across an ohmic resistor? (Current also doubles, provided the resistance stays constant.)
  * Why is it important to keep the temperature constant when testing Ohm’s law? (Because resistance can change with temperature, altering the relationship.)