Calculate voltage using Ohm's Law: V = I × R (Volts = Amps × Ohms) or V = P / I (Volts = Watts ÷ Amps). Perfect for electronics, circuit design, and electrical engineering.
📊 Calculated Voltage
0 V
V = I × R = 2A × 110Ω = 220 Volts
📖 What is Voltage?
Voltage (measured in Volts, symbol V) is the electrical potential difference that pushes electric current through a circuit. Named after Italian physicist Alessandro Volta (1745-1827), inventor of the electric battery. One volt is defined as the potential difference that drives one ampere of current against one ohm of resistance.
⚡ Ohm's Law Explained
Ohm's Law is a fundamental principle in electrical engineering stating that the current through a conductor between two points is directly proportional to the voltage across the two points. The three basic formulas are:
V = I × R | I = V / R | R = V / I Also: P = V × I | V = P / I | I = P / V
Where: V = Voltage (Volts) I = Current (Amperes) R = Resistance (Ohms) P = Power (Watts)
📊 Common Voltage Reference Table
Device / Application
Typical Voltage
Current (approx)
Power
Household Outlet (India)
220-240V AC
5-15A
1100-3600W
USB Charger
5V DC
1-3A
5-15W
Car Battery
12V DC
30-100A (starter)
360-1200W
LED Bulb
12V / 220V
0.1-0.5A
5-15W
Laptop Adapter
19V DC
3-5A
45-90W
Mobile Phone Battery
3.7V DC
1-2A charging
3.7-7.4W
Electric Iron
220V AC
4-6A
800-1200W
🌍 Standard Voltages Around the World
Country/Region
Standard Voltage
Frequency
Plug Type
India, UK, Europe, Australia
220-240V
50Hz
C, D, E, F, G
USA, Canada, Japan
110-120V
60Hz
A, B
Brazil, South Africa
220-230V
50/60Hz
C, N
China, Australia
220-240V
50Hz
A, C, I
💡 How to Use This Voltage Calculator
Method 1 (V = I × R): Enter current in Amperes (A) and resistance in Ohms (Ω)
Method 2 (V = P / I): Enter power in Watts (W) and current in Amperes (A)
Use preset buttons for common electrical values
Results update in real-time as you type
Use for DC circuits; for AC circuits, use RMS values
🔧 Practical Applications
Household Circuits: India uses 220V AC - ensure appliances match this rating
Car Electronics: 12V DC - check voltage before connecting devices
USB Devices: 5V DC - all USB chargers provide standard 5V
LED Lighting: Common voltages: 12V, 24V, 220V - verify before installation
📝 What is Voltage Drop?
Voltage drop is the reduction in voltage along a wire or circuit due to resistance. It's calculated using: V_drop = I × R_wire. For long cable runs, keep voltage drop under 3-5% for efficient operation. This is especially important for:
Solar panel installations (long DC cable runs)
LED lighting systems
Power transmission lines
Automotive wiring
⚡ Ohm's Law Triangle
V = I × R | I = V / R | R = V / I Also: P = V × I | V = P / I | I = P / V
📝 Frequently Asked Questions (FAQ)
❓ What is Ohm's Law? ▼
Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. The formula is V = I × R, where V is voltage (volts), I is current (amperes), and R is resistance (ohms). It is the foundation of electrical engineering.
❓ How do I calculate voltage using Ohm's Law? ▼
To calculate voltage, multiply current (in Amperes) by resistance (in Ohms): V = I × R. For example, 2 Amps × 110 Ohms = 220 Volts. Alternatively, if you know power and current, use V = P / I. Example: 1000W ÷ 5A = 200V.
❓ What is the difference between AC and DC voltage? ▼
AC (Alternating Current) voltage changes direction periodically (like household outlets, 220V AC at 50Hz). DC (Direct Current) voltage flows constantly in one direction (like batteries, 12V DC, 5V USB). Both follow Ohm's Law for basic calculations, but AC circuits may involve impedance and power factor.
❓ What is the standard household voltage in different countries? ▼
India, UK, Europe, Australia: 220-240V AC at 50Hz. USA, Canada, Japan: 110-120V AC at 60Hz. Most modern electronic devices support both voltages (100-240V) but always check the label before use.
❓ How to measure voltage in a circuit? ▼
Use a multimeter set to voltage (V) mode. For DC voltage (batteries, circuits), connect red probe to positive and black to negative. For AC voltage (household outlets), connect probes across the terminals. For safety, never measure high voltage without proper training and equipment.
❓ What is voltage drop and how to calculate it? ▼
Voltage drop is the reduction in voltage along a wire or circuit due to resistance. Calculate using V_drop = I × R_wire. For example, 10A current through a 0.5Ω wire causes 5V drop. Keep voltage drop under 3-5% for efficient operation in long cable runs.
💡 Educational Note: Voltage is named after Italian physicist Alessandro Volta (1745-1827), who invented the first electric battery (the Voltaic Pile). One volt is defined as the potential difference that drives one ampere of current against one ohm of resistance. Understanding voltage is essential for all electrical and electronic work.