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ELECTRIC CURRENT A flow of charge from one place to another. The unit is Ampere , which equal to a flow of 1 coulomb per second.

Moving charges as a current ,[object Object],[object Object],[object Object]

When moving charges is not a current ,[object Object],[object Object],[object Object],[object Object]

Electric current in a conductor ,[object Object],Isolated conductor charges

continuation: ,[object Object],Battery + - Conductor Charges Direction of charges

continuation: ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

continuation: - - - - - - t = t 0 t = t 0 + 1 s plane plane

continuation: ,[object Object],a b c a’ b’ c’ I I

Sample problem: ,[object Object]

Current is a scalar quantity ,[object Object],[object Object]

continuation: I 0 I 1 I 2 I 0 = I 1 + I 2

DIRECTION OF CURRENT ,[object Object],[object Object]

continuation: ,[object Object],[object Object]

Drift Speed ,[object Object],Where: I = electric current (A) n = charge concentration v d = drift velocity (m/s) e = charge of electron A = cross-sectional area of conductor(m 2 ) ,[object Object],I in I in A

Current Density ,[object Object],[object Object],Where: I = electric current (A) J = current density (A/m 2 ) n = charge concentration v d = drift velocity (m/s) e = charge of electron A = cross-sectional area of conductor(m 2 )

Sample Problem: ,[object Object]

Types of Current ,[object Object],[object Object],[object Object],[object Object],[object Object]

continuation: ,[object Object],[object Object],[object Object],[object Object],[object Object]

Types of Current ,[object Object],Alternating Current I (A) t (s) I (A) t (s)

Electric Resistance ,[object Object],[object Object],Where: R = Resistance (Ohm, Ω ) ρ = resistivity ( Ω m) L = Length of the wire (m) A = cross-sectional area of a wire(m 2 )

Sample Problem: ,[object Object],ρ L A

Resistivity & Conductivity ,[object Object],[object Object],[object Object],Conducting material Electric field

continuation: ,[object Object],[object Object],Where: ρ = resistivity ( Ω m) E = electric field (N/c) J = current density (A/m 2 )

[object Object],[object Object],[object Object],continuation:

Variation of Resistivity with Temperature ,[object Object],400 200 0 1200 1400 2 8 0 4 6 10 600 800 1000 Resistivity 10 -8 Ω m Room temperature Temperature (Kelvin)

Variation of Resistivity with Temperature ,[object Object],Where: ρ = resistivity ( Ω m) ρ 0 = resistivity at room temperature ( Ω m) T = temperature (Kelvin,K) T 0 = room temperature (K) α = coefficient of resistivity (K -1 )

Current Potential Difference graph of a 1000 W resistor , an Ohmic device. -4 -2 0 +2 +4 -2 +2 0 Current (mA) Potential Difference (V)

Current vs Potential Difference graph of a pn junction diode , a non-ohmic device. -4 -2 0 +2 +4 -2 +2 0 Current (mA) Potential Difference (V)

Single Loop Circuit ,[object Object],[object Object],EMF Device Maintain potential difference. Provides steady flow of charge. EMF stand for Electromotive force . R EMF I + - + - I

The Resistor ,[object Object],[object Object],[object Object],[object Object],[object Object]

Electromotive Force ,[object Object],[object Object],[object Object],EMF

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],continuation: EMF r i

continuation: ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Sample Problem: ,[object Object],[object Object],[object Object]

Resistors in Single Loop Circuit

[object Object],Resistors in Series Circuit. R 3 V T I T + - + R 2 + R 1 + - - - R T

Equivalent resistance in a Series Circuit

[object Object],R 3 V T I T + - + R 2 + R 1 + - - - R T I 3 I 2 I 1

Equivalent resistance in a Parallel Circuit

Resistors in Single Loop Circuit ,[object Object],R 3 V T I T + - + R 2 + R 1 + - - - R T

The Power in the Circuits ,[object Object]

continuation: ,[object Object],[object Object],[object Object],Q

continuation: ,[object Object],[object Object],[object Object],[object Object]

continuation: ,[object Object]

MULTILOOP CIRCUIT ,[object Object],[object Object]

What happen when one component in a series circuit was cut-off?

What happen when one component in a multiloop circuit was cut-off?

continuation: ,[object Object],[object Object],[object Object],Junction current

GUSTAV KIRCHHOFF ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],KIRCHHOFF’S LAW R 2 + Emf 1 + - R 1 + Emf 2 + - R 3 + Loop 1 Loop 2 I 1 I 2 I 3 -

[object Object],KIRCHHOFF’S LAW R 2 + ε 1 + - R 1 + ε 2 + - R 3 Junction point I 1 I 3 I 2 +

Sample Problem: ,[object Object],10 Ω + 9v + - 15 Ω + 12v + - 5 Ω I 1 I 3 I 2 +

RC CIRCUIT (Resistor and Capacitor in a circuit)

[object Object],R + - C S 1 S 2 ε + - Where: ε = Batteries (Emf) S 1 & S 2 = Switches R = Resistor C = Capacitor Open Close

Charging a capacitor R + - C S 1 S 2 ε + - I I I I I closed open Where: V R = Potential difference across the resistor. V C = Potential difference across the capacitor. I

continuation ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],continuation

Sample Problem: ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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