Coulomb Defined by Current and Time

Steps:

• Recall that electric charge (coulomb) is the amount of charge transferred by a current over time.
• Use the formula Q = I × t, where Q is charge in coulombs, I is current in amperes, and t is time in seconds.
• Identify that 1 coulomb equals 1 ampere flowing for 1 second.
• Confirm the base SI units: ampere for current and second for time.

Why A is correct:

• The SI definition states 1 coulomb = 1 ampere × 1 second, directly from the charge-current-time relation.

Why the others are wrong:

• B: Ampere and volt define power (watt), not charge.
• C: Volt and ohm define current (ampere), not charge.
• D: Volt and second define capacitance (farad), not charge.

Final answer: A