Question

Why does voltage go to zero?

Answer 1

Voltage going to zero can happen for a few different reasons, depending on the situation. Here are some common explanations:

### 1. **Power Loss or Shutdown**
   - If a circuit is turned off or disconnected from its power source, the voltage in the circuit can drop to zero. For example, if you turn off a switch or unplug an electrical device, the voltage across the device would go to zero because no power is being supplied.

### 2. **Open Circuit**
   - In an open circuit, there's no continuous path for current to flow, and thus, the voltage can drop to zero across certain parts of the circuit. If you measure the voltage across an open switch or a break in the circuit, you would get a reading of zero.

### 3. **Short Circuit**
   - A short circuit occurs when a low-resistance path forms between two points that shouldn't be directly connected, like between two wires in a power supply. This can cause the voltage to drop to zero or near zero because the current takes the shortest path (which can be a very low-voltage path), bypassing other parts of the circuit.

### 4. **Voltage Drop**
   - In a resistive circuit (like when current flows through a resistor), you can experience a voltage drop across the components. If the resistance is too high, or the power supply can't deliver enough energy, the voltage across the load might drop to zero, especially when the power supply is overloaded or failing.

### 5. **Capacitor Discharge**
   - If there’s a capacitor in the circuit, it stores charge and maintains a certain voltage across it. When the capacitor discharges, the voltage across it will decrease and eventually go to zero as the stored energy is used up or dissipates.

### 6. **Grounding**
   - When a circuit is grounded (connected to the Earth), certain points in the circuit can be at zero volts relative to the ground. This doesn't mean the whole circuit voltage is zero, but some parts of the circuit might be referenced to ground, which is considered zero voltage.

### 7. **Power Supply Failure**
   - If a power supply fails or is turned off, voltage at its output will drop to zero. This could happen due to a malfunction or a loss of input power.

If you’re troubleshooting and seeing voltage go to zero, it’s usually a sign that either the power source has been interrupted, there’s a break in the circuit, or something is wrong with the components. You can check the connections, power source, and components to find the cause.