Determining the current when the power and voltage are known is fundamental for various electrical applications. This relationship is expressed through a specific formula, which we will explore with practical examples.
The Formula: \( P = V \cdot I \)
To find the current, we rearrange the formula as follows:
\[ I = \dfrac{P}{V} \]
Where:
- \( P \) is the electric power (measured in watts, W)
- \( V \) is the voltage (measured in volts, V)
- \( I \) is the current (measured in amperes, A)
Example 1: Current of a Hair Dryer
Question: A hair dryer operates at 1800 watts and 120 volts. What is the current?
Calculation:
Given:
- \( P = 1800 \) W
- \( V = 120 \) V
Using the formula:
\[ I = \dfrac{P}{V} = \dfrac{1800}{120} = 15 \, \text{A} \]
Result: The current of the hair dryer is 15 amperes.
Example 2: Current of a Refrigerator
Question: A refrigerator uses 200 watts of power and operates at 240 volts. What is the current?
Calculation:
Given:
- \( P = 200 \) W
- \( V = 240 \) V
Using the formula:
\[ I = \dfrac{P}{V} = \dfrac{200}{240} \approx 0.833 \, \text{A} \]
Result: The current of the refrigerator is approximately 0.833 amperes.
Example 3: Current of a Phone Charger
Question: A phone charger provides 10 watts of power and operates at 5 volts. What is the current?
Calculation:
Given:
- \( P = 10 \) W
- \( V = 5 \) V
Using the formula:
\[ I = \dfrac{P}{V} = \dfrac{10}{5} = 2 \, \text{A} \]
Result: The current of the phone charger is 2 amperes.
