Class notes Electronics (Elecs)

ELECTRICAL ELEMENTS/ELECTRICITY & MAGNETISM
OHM'S LAW : 1 COULOMB = 6.24 ×
𝑣
𝐼=𝑅 1018 𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛𝑠
R=𝜌 𝐴𝐿 (specific resistance)
COULOMB'S LAW
RESISTIVITY OF COPPER: 1. LIKE CHARGES REPEL,
1.7 × 10−8 𝛺 ⋅ 𝑚 2. UNLIKE CHARGES ATTRACT
𝑞1 𝑞2 1
𝐹=𝑘 2 , 𝑘=
TEMPERATURE EFFECT: 𝑑 4𝜋є
𝑅2 = 𝑅1 (1+∝ (𝑇2 − 𝑇1 ))
ELECTRIC FIELD:
ELECTROMOTIVE FORCE: EMF 𝑉 𝑄 𝐹
є= 𝑑 = 𝑘 𝑑2 = 𝑞
TYPES OF MATERIALS 𝑄
CONDUCTORS GAUSS LAW: 𝜓 = = 𝐸𝐴𝑐𝑜𝑠Ѳ
𝜀0
1 < VALENCE ELECTRONS < 4 𝜓 𝑞
ELECTRIC FLUX DENSITY: 𝐷 = = = 𝜀𝐸
(metals: copper, silver, gold) 𝐴 4𝜋𝑟 2
INSULATORS
4 < VALENCE ELECTRONS < 8
(rubber, glass)

FATAL TO HEART: 𝐼 ≥ 0.1𝐴

, 𝑄 𝐴
CAPACITANCE: C= ; C=𝜀0 𝜀𝑟 𝑑
𝑉 INDUCTANCE IN SERIES: 𝐿 𝑇 = 𝐿1 + 𝐿2

𝐿 𝐿
INDUCTANCE IN PARALLEL: 𝐿 𝑇 = 𝐿 1+𝐿2
1 2
𝑑𝑖
V= 𝐿 𝑑𝑡
1
i= 𝐿 ∫ 𝑣 𝑑𝑡
MUTUAL INDUCTANCE: 𝑀 = 𝑘√𝐿1 𝐿2

𝐶1 𝐶2
CAPACITANCE IN SERIES: 𝐶𝑇 =𝐶
1 +𝐶2

CAPACITANCE IN PARALLEL: 𝐶𝑇 = 𝐶1 + 𝐶2
1
𝑉= ∫ ⅈ 𝑑𝑡
𝐶
𝑑𝑣
𝐼=𝐶
𝑑𝑡 ANION (-) -ANODE
CATION (+) -CATHODE

, 𝜑 CURRRENT DIVISION THEOREM (VDT)
MAGNETIC FLUX DENSITY: B= 𝐴
𝑅2
𝐼 I1 = 𝐼𝑇 𝑅
1 +𝑅2
MAGNETIC FIELD: B= μ 2𝜋𝑟
𝑅1
I2 = 𝐼𝑇
𝑅1 +𝑅2

DC CIRCUITS:
𝑤𝑜𝑟𝑘 𝑄
ELECTRIC POWER (P) = = 𝑣 = 𝐼𝑉
𝑡𝑖𝑚𝑒 𝑡

JOULE'S LAW (POWER DISSIPATION)
𝑉2
P= 𝑅 = 𝐼 2 𝑅


VOLTAGE DIVISION THEOREM (VDT)

𝑅1
V1 = 𝐸
𝑅1+𝑅2

𝑅2
V2 = 𝐸
𝑅1+𝑅2

,