Study of Open and Short Circuit Conditions

401

Aim: To study open and short circuit conditions in a simple circuit

Apparatus required

SL No.ApparatusSpecificationQty
1Voltmeter0 – 300V3
2Ammeter0 – 2A2
3Batten Holder2
4Incandescent lamp40W, 230V2
5SwitchSPST2

Theory

Imagine a dam. When the reservoir is full, water is supposed to fall off from the top, traveling the distance equal to the height of the dam. But you punch a hole at the bottom. Now the path of water is shortened, and the small hole you have made makes the whole dam collapse because of high pressure at the bottom. This is the principle of a short circuit.
In the same way, imagine a circuit in which current is supposed to travel from the positive terminal of a battery, into a wire which is connected to a bulb, and back to the negative terminal of the battery. But you shorten the path of current by directly connecting the positive terminal to the negative and the battery explodes. This is called short-circuiting.


In household, current has to travel through electrical appliances. But you are standing on the ground without any insulation between you and it, and you touch the live wire. Since you are at zero potential, (ground) the current (which is at higher potential) will travel through you, which is a short path for electricity And you will burst into flames. So you are causing a short circuit.

A short circuit is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance.
This results in an excessive current flowing through the circuit. The opposite of a short circuit is an “open circuit”, which is infinite resistance between two nodes

Procedure

  • Connect the circuit as shown in the circuit diagram
  • Keep the switch 1 in off position and switch 2 in On position
  • Note the potential difference across the two lamps, the main circuit current, the current through lamp L1 and supply voltage
  • Repeat step 3 with both switches SW1 and SW2 On position
  • Also, step 3 with both switches SW1 and SW2 Off position

Observations and Calculations

Open Circuit: Both the switches are Off.
Closed Circuit: Only one switch is On.
Short Circuit: Both the switches are On.

Tabular Column

Circuit conditionSupply
Voltage VS
(Volts)
Total Current
I (Amps)
Current
Through lamp L1,
I1 (Amps)
Voltage
Across L1, V1
Voltage
Across L2, V2
Open
Closed
Short

Inference

Potential difference and current during normal working conditions have been studied for simple circuit.

1 Comment
  1. BrianFEF says

    Love the website– very user pleasant and lots to see!

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