What increases when wires are in a loose connection? why is heat generated?

Question

formulas P=VI or V=IR or P=I^2 R

What is increasing? is it curent, voltage, or resistance?

i know that wires heat up when loose or when it is too small..

Answer 1

you know  resistance is only the property of matter which is directly responsible for the generation of heat through a circuit.

As you have found that heat is being generating so i dont find any doubt that resistance is increases when the circuit undergoes a

loose wire connection.

This is because there creates a small space between the connections which is neglegible for us but it takes more energy loss for the electrons to cover up this small space.

                                Can you agree with me?

Answer 2

Resistance increases. When wires are loose, the area which the current must flow through decreases, thus increasing the resistance.

Answer 3

In a circuit with a loose connection the overall resistance of that circuit increases.

To explain further consider a simple domestic lighting circuit.

In a correctly designed healthy circuit (No loose connections) the resistance of the cables and connections are very low in comparison to the Resistance of the light bulb. Electric current flows easily through the cables and connections with relatively low increase in temperature.

At the point of a loose connection a higher than normal resistance is encountered, effectively this resistance is in series with the light bulb.

The result is that the voltage across the light bulb decreases and a voltage appears across the loose connection (Simple series circuit) This voltage when multiplied by the circuit current gives a power value this power is dissipated in the form of heat at the loose connection.

The resistance increases at the loose connection because the 2 metals are not properly in contact with each other effectively reducing the cross sectional area at the joint.

If the loose connection is very loose the 2 metals may actually break apart a small distance (possibly from external vibration) causing an arc to jump from one side to the other this significantly increases the temperature at the loose connection.  

A high resistance joint or an arcing joint are both potentially dangerous and the sources of many electrical fires.