If the positive and negative terminals of a power source, such as a battery, are directly connected, a circuit is formed and current flows between the two terminals. The specific outcome depends on the characteristics of the power source and the circuit elements connected to it:
Battery: If you connect the positive and negative terminals of a battery directly, it creates a short circuit. A short circuit allows a large amount of current to flow quickly and uncontrollably, bypassing the normal circuit path. This can result in a rapid discharge of the battery's energy and generate a significant amount of heat. In extreme cases, it may cause the battery to overheat, leak, or even explode. Short circuits are generally not recommended and can be dangerous.
Power Supply: For a power supply or other electrical source, connecting the positive and negative terminals directly creates a complete circuit. The current will flow from the positive terminal, through the circuit, and back to the negative terminal. The behavior and consequences depend on the components connected to the circuit. If there are resistors, motors, or other devices, they will receive current and operate according to their electrical characteristics.
In both cases, connecting the positive and negative terminals creates a low-resistance path for the electric current, allowing it to flow continuously. This can have different effects depending on the specific situation, the power source, and the components involved. However, it's important to note that short circuits can be dangerous and should be avoided, especially with batteries or other high-energy sources.