The Charge Parade

Why it matters

Tap a switch and the bulb lights the same instant — yet the charges themselves crawl slower than a snail. So what actually flows in a wire?

The idea in plain words

Every symbol earns its place. Tap each one.

I = Q ÷ t

A bulb passes 90 C of charge in one minute. Find the current.

I = 1.5 A

• ampere (A): I — electric current — the rate of flow of charge
• coulomb (C): Q — charge that passes the point
• second (s): t — time taken for it to pass
• t = 1 minute = 60 s
• I = Q ÷ t = 90 ÷ 60

Predict first

A charge of 6 coulombs passes a point in a wire in 3 seconds. How big is the current?

Current is a RATE: I = Q ÷ t = 6 ÷ 3 = 2 A. One ampere means one coulomb marching past every second.

• 2 ampere — correct
• 18 ampere
• 6 ampere — charge and current are the same thing

What you do

Slide the charge and the time to control the current — hit both targets. Then flip the view: conventional current and the electrons go opposite ways!

Check yourself

Which way does conventional current flow in the outside circuit?

Conventional current keeps the historical + → − direction. Electrons, being negative, drift the opposite way.

5 C of charge passes in 10 s. The current is…

I = Q ÷ t = 5 ÷ 10 = 0.5 A.

Same charge, but it takes twice as long to pass. The current…

Current is charge per second — stretch the time, thin the flow.

• From + terminal to − terminal — correct
• From − to +, the way the electrons drift
• Both directions at once
• 0.5 A — correct
• 50 A
• 5 A
• halves — correct
• doubles
• stays the same