phy17-1

# phy17-1 - carrier q – ΔQ =(n A Δx q • The drift speed...

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17.1 Electric Current The current is the rate at which the charge flows through a surface – Look at the charges flowing perpendicularly through a surface of area A The SI unit of current is Ampere (A) – 1 A = 1 C/s av Q I t The direction of the current is the direction positive charge would flow This is known as conventional current direction It is common to refer to a moving charge as a mobile charge carrier A charge carrier can be positive or negative 17.2 Microscopic View of Current

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Current and Drift Speed The total charge is the number of carriers times the charge per

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Unformatted text preview: carrier, q – ΔQ = (n A Δx) q • The drift speed, v d , is the speed at which the carriers move – v d = Δx/ Δt • Rewritten: ΔQ = (n A v d Δt) q • Finally, current, I = ΔQ/Δt = nqv d A Meters in a Circuits: Voltmeter – Ammeter • An ammeter is used to measure current I – In line with the bulb, all the charge passing through the bulb also must pass through the meter • A voltmeter is used to measure voltage V (potential difference) – Connects to the two contacts of the bulb...
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phy17-1 - carrier q – ΔQ =(n A Δx q • The drift speed...

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