Electric Circuits, Current, and Voltage Fundamentals

Which statement best defines an electric circuit according to the lesson?

• A straight wire that lets charges escape into the air

• A closed loop or pathway that allows continuous flow of electric charge

• Any arrangement of components where charges are stored but cannot move

• A device that creates electric charge without a path

Electric current is measured as the amount of charge passing a point per unit time. Which equation correctly represents this relationship?

• I = W/q

• I = Δq/Δt

• I = V·q

• I = V/Δt

What are the standard SI units for the quantities in the current equation I = Δq/Δt?

• I in amperes (A), Δq in coulombs (C), Δt in seconds (s)

• I in volts (V), Δq in joules (J), Δt in seconds (s)

• I in coulombs (C), Δq in amperes (A), Δt in minutes (min)

• I in ohms (Ω), Δq in coulombs (C), Δt in hours (h)

If 6 coulombs of charge pass a point in 2 seconds, what is the current?

• 1 A

• 2 A

• 3 A

• 6 A

Which description best characterizes direct current (DC) as presented?

• Alternating direction and varying magnitude, supplied by wall outlets

• Unidirectional flow with constant magnitude, commonly produced by batteries

• Random motion of charges in a conductor, produced by friction

• Flow that requires no closed path and can jump across gaps

On a battery, seeing a + and − symbol most directly indicates which aspect of DC?

• The battery’s total energy storage

• The direction of DC flow from positive to negative terminal

• That the battery alternates polarity periodically

• The magnitude of the current independent of the circuit

Electric potential difference (voltage) is defined in the notes as the energy required to move a unit charge between two points. Which formula corresponds to this definition?

• V = W/q

• V = q/W

• V = I·R

• V = Δq/Δt

A charge of 10 coulombs moves through a potential difference of 5 volts. Based on V = W/q, how much work is done?

• 2 J

• 5 J

• 10 J

• 50 J

Recall the definition: In electric circuits, power is defined as the rate at which energy is transferred or converted. Which equation correctly represents electric power?

• P = IV

• P = I/V

• P = V/I

Voltage and current relationship: If resistance remains constant, what happens to current when voltage increases?

• Current increases

• Current decreases

• Current stays zero

• Current becomes undefined