3500 T2 Electronics

Briefly explain Ohm’s law.

• V across resistor = directly ≈ how much current flows thru it, scaled by Ω value.

• ↑ Ω for the same 𝗜 = ↑ 𝗩 needed to push it thru; ↑ 𝗜 for the same Ω = ↑ 𝗩 required.

What = a series circuit @ its core?

Components connected in ONE single path/line → same 𝗜 flows thru EVERY component, one after another.

Big picture — why does a 𝗩 divider matter?

Total 𝗩 (V_in) → “used up” piece by piece across each resistor → lets you create a SMALLER, specific 𝗩 @ any pt in circuit from one ↑ 𝗩 source.

How do you calculate a 𝗩 divider, step by step?

• I = V_in/(R1 + R2) → find total 𝗜 (add resistors since 𝗜 flows thru both)

• V_R1 = 𝗜 × R1 → 𝗩 dropped across R1.

• V2 = V_in - V_R1 → what’s left over after R1’s drop = your answer.

• Quick sanity check: V_R2 = I × R2 → should equal V2 directly.

What’s the key difference b/w series + parallel circuits?

• Series: same CURRENT flows through everything, VOLTAGE gets divided/split

• Parallel: same VOLTAGE appears across everything, CURRENT gets divided/split

What = a parallel circuit, @ its core?

Components connected side-by-side, sharing SAME two connection pts ∴ same 𝗩 appears across EVERY component.

How do you calculate total Ω in parallel?

1/R = 1/R1 + 1/R2 → solve for R ∴ total R = always SMALLER than smallest individual resistor.

How do you calc 𝗜 thru each resistor?

𝗜1 = V_in/R1; 𝗜2 = V_in/R2 ∴ same V_in plugged → each, since 𝗩 shared.

What’s the difference b/w the series formula (V/R = V_R1/R1 = V_R2/R2) + the parallel formula (V = I1 × R1 = I2 × R2)

• Series formula: V/R terms all equal I ∴ confirms CURRENT is shared/constant across the circuit

• Parallel formula: I×R terms all equal V ∴ confirms VOLTAGE is shared/constant across the circuit

(Both look like "= = =" chains, but series chains current-equivalent expressions ≠ parallel chains voltage-equivalent expressions)

What = loading error?

Measuring device’s own Ω changes circuit it’s measuring ∴ measurement becomes inacc.

How to ↓ loading err for ammeters vs. voltmeters?

• Ammeter → placed in SERIES → Ω adds to circuit ∴ needs ↓ Ω (~0Ω) to ↓ ∆ in circuit’s 𝗜

• Voltmeter → placed in PARALLEL → Ω creates alt path, pulling 𝗜 aways ∴ needs ↑ Ω (~∞Ω) so it barely draws any 𝗜 away

? ∆ b/w capacitor + resistor.

• Unlike resistor (which lets 𝗜 flow continuously thru it), a capacity STORES electrical charge on its two plates, separated by that gap.

• 𝗜 can’t literally flow thru the gap, but charge builds up on one side + depletes on the other, which effectively acts like 𝗜 = flowing, while the capacitor = charging

What’s a capacitor? How does it work?

• Two plates, gap b/w them (no direct 𝗜 flow across) ∴ charge builds up on each side instead.

• It fills up w/ e⁻’s when energized + releases them when supply stops.

How does 𝗩 rise fast → slow?

• START (empty capacitor): big gap b/w battery V and capacitor's V (0V) ∴ pushes charge onto plates fast

• Charge builds → capacitor's V climbs closer to battery V → gap shrinks

• Smaller gap = ↓ "push" driving new charge on ∴ charging ↓ slows

• Capacitor V ≈ battery V → barely any push left → charging plateaus

What’s direct 𝗜? What’s alternating 𝗜? What does each look like in a graph?

• cons V over time; simple flat line

• oscillating V up + down continuously over time; line = wave

Define the ff: V_pk-pk, _-m, _-RMS?

• V_pk-pk: distance tot from very top of wave to very bottom

• V_m: HALF of that pk-pk distance — measured from middle (zero line_ up to just the top peak

• V_RMS: the “effective” DC-equivalent 𝗩

What;’s the formula relating pk-pk, m, + RMS voltages?

/$\frac12V_{pk-pk}=V_{m}=\left(\frac{2}{\sqrt2}\right)V_{RMS}$

What’s the ∆ b/w Per + Hz?

• Per: how long ONE full wave cycle takes

• Hz = f = 1/T — how many complete cycles happen per second

What = V_RMS + why it used instead of amp?

• AC 𝗩 constantly changes (sine wave) ∴ no single “the 𝗩” moment to pt to.

• V_RMS = “effective” steady value ∴ if replaced w DC, delivers SAME power

• V_RMS = V_amplitude / √2 ∴ RMS always SMALLER than peak (accounts for whole wave shape, not just top)

What is impedance (Z) + why does AC need it instead of just R?

• DC: V and I are flat/constant ∴ simple R (resistance) is enough

• AC: V and I are waves, constantly changing ∴ components like capacitors cause TIMING shifts, not just resistance ∴ need Z (impedance) to capture both effects

Z = Z_real + Z_im × i — what does the two parts x̄?

• Z_real = behaves like normal Ω (opposes 𝗜, no timing shift) = the “old” R

• Z_im (imaginary part) = NEW, captures the TIMING/PHASE SHIFT effect (caused by capacitors/inductors taking time to charge/react)

What does the “phase shift” on the graph actually show?

• V + I waves peak @ DIFFERENT times, not aligned ∴ that offset = what Z_im mathematically reps (caused by capacitors, as charging takes time, ∴ 𝗜 reacts sooner/later than 𝗩)

• Pure resistor (no cap/ind) → V + I stay in-sync (Z_im = 0)

• Capacitor/inductor added → V + I shift out of synce (Z_im ≠ 0)