Voltage, also known as electric potential difference, is the force that drives electric current through a conductor. It is measured in volts (V). There are two main types of voltage: Alternating Current (AC) and Direct Current (DC).

Voltage in a circuit can be calculated using Ohm’s Law and Kirchhoff’s Voltage Law (KVL). Here are some basic formulas:

**Ohm’s Law:***V = I × R*(Voltage = Current × Resistance)**Series Circuit:***V*_{total}= V_{1}+ V_{2}+ ... + V_{n}**Parallel Circuit:***1 / V*_{total}= 1 / V_{1}+ 1 / V_{2}+ ... + 1 / V_{n}

**Direction of Flow:**DC has a constant direction, while AC reverses direction periodically.**Voltage Level:**DC voltage is steady, whereas AC voltage alternates between positive and negative peaks.**Transmission:**AC is more efficient for transmitting electricity over long distances due to lower energy losses, while DC is more suitable for short-distance and low-voltage applications.**Use Cases:**DC is commonly used in battery-powered devices, electronics, and automotive applications, while AC is used for general household power supply, industrial machinery, and power grids.

Direct Current (DC) is a type of electrical current that flows in one direction only. The voltage in a DC circuit remains constant over time, providing a steady stream of electricity. Batteries, solar cells, and DC power supplies are common sources of DC voltage.

**Unidirectional Flow:**DC voltage causes current to flow in a single direction from the positive to the negative terminal.**Constant Voltage:**The voltage level remains constant, providing a stable power supply.**Applications:**DC is commonly used in electronic devices, automotive systems, and portable gadgets like smartphones and laptops.

Consider a simple circuit with a battery of 9 volts and a resistor of 3 ohms. Using Ohm's Law, we can calculate the current flowing through the circuit.

**I = V / R = 9V / 3Ω = 3A**

This means a current of 3 amperes flows through the circuit.

Ohm's Law CalculatorAlternating Current (AC) is a type of electrical current that periodically reverses direction. The voltage in an AC circuit varies sinusoidally with time, meaning it goes through cycles of positive and negative values. Power plants generate AC voltage, which is then transmitted through power lines to homes and businesses.

**Bidirectional Flow:**AC voltage causes current to flow back and forth, reversing direction periodically.**Varying Voltage:**The voltage level alternates between positive and negative values, creating a sine wave.**Applications:**AC is used for household appliances, industrial equipment, and large-scale power distribution due to its efficiency in transmitting over long distances.

In an AC circuit, the voltage can be described by the equation:

**V(t) = V _{peak} sin(2πft)**

- V(t) is the instantaneous voltage
- V
_{peak}is the peak voltage - f is the frequency (in hertz)
- t is time (in seconds)

For a standard household AC supply with a peak voltage of 170 volts and a frequency of 60 Hz, the instantaneous voltage at time t = 0.01 seconds can be calculated as:

**V(0.01) = 170 sin(2π × 60 × 0.01) ≈ 170 × -0.588 ≈ -99.96V**

This indicates that the voltage at t = 0.01 seconds is approximately -99.96 volts.

Calculate the voltage drop in a circuit.

Voltage Drop = (2 * Current * Length * Resistance) / (Conductor Size)

Voltage Drop = (2 * Current * Length * 0.3048 * 12.9) / (Conductor Size * Power Factor^1.5)

- The constant factor 2 is used because the voltage drop is calculated as a two-way trip (to and from the load).
**Current:**The current in amperes flowing through the wire.**Length:**The length of the wire in feet.**Conductor Size:**The size of the conductor (wire) in AWG (American Wire Gauge).**Power Factor:**The power factor of the electrical system.

Voltage regulation is important to maintain a constant voltage level in automation systems. Voltage regulators are used to keep the voltage within desired limits despite variations in load or input voltage.

Example calculation for voltage regulation:

**Task:**Determine the output voltage of a voltage regulator with an input voltage of 24 volts (V) and a dropout voltage of 2 volts (V).**Solution:**Use the voltage regulation formula:*V*._{out}= V_{in}- V_{dropout}*V*_{out}= 24V - 2V = 22V

Kirchhoff's Voltage Law states that the sum of all electrical potential differences (voltages) around any closed network is zero. This law is based on the principle of conservation of energy.

**Formula:** *ΣV = 0*

**ΣV:**Sum of voltages around the closed loop

**Example Calculation:**

**Task:**Determine the unknown voltage V_{x}in a loop where V_{1}= 10 V, V_{2}= 5 V, and V_{3}= -3 V.**Solution:**Apply KVL:*ΣV = 0*-
*10 V + 5 V + V*_{x}- 3 V = 0*12 V + V*_{x}= 0*V*_{x}= -12 V

In three-phase systems, the relationship between line voltage (V_{L}) and phase voltage (V_{ph}) depends on the connection type: Star (Wye) or Delta.

In a star connection, the line voltage is √3 times the phase voltage.

**Formula:** *V _{L} = √3 × V_{ph}*

**V**Line voltage (volts, V)_{L}:**V**Phase voltage (volts, V)_{ph}:

**Example Calculation:**

**Task:**Calculate the line voltage for a star-connected system with a phase voltage of 230 V.**Solution:**Use the formula*V*._{L}= √3 × V_{ph}-
*V*_{L}= √3 × 230 V ≈ 398 V

In a delta connection, the line voltage is equal to the phase voltage.

**Formula:** *V _{L} = V_{ph}*

**V**Line voltage (volts, V)_{L}:**V**Phase voltage (volts, V)_{ph}:

**Example Calculation:**

**Task:**Calculate the line voltage for a delta-connected system with a phase voltage of 230 V.**Solution:**Use the formula*V*._{L}= V_{ph}*V*_{L}= 230 V