Applications of electromagnetic induction
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All 12 Flashcards — Applications of electromagnetic induction
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Question
How does an AC generator work?
Answer
A **coil is spun** in a magnetic field. The changing flux induces a **sinusoidal emf** — alternating current (AC).
Question
When is the generator emf at its peak?
Answer
When the coil is **edge-on** to the field — the flux is changing **fastest** there.
Question
Peak emf of an AC generator?
Answer
$\varepsilon_0 = BAN\omega$ — increase any of **B**, **A**, **N** or **ω** to raise it.
Question
What does B, A, N, ω each stand for in ε₀ = BANω?
Answer
**B** flux density, **A** coil area, **N** turns, **ω** angular frequency of rotation.
Question
Define the rms value of an AC.
Answer
The **steady DC value** that delivers the **same average power** (same heating) as the AC.
Question
Convert peak to rms (sine wave)?
Answer
$V_{rms} = \dfrac{V_0}{\sqrt{2}}$ and $I_{rms} = \dfrac{I_0}{\sqrt{2}}$ — divide the peak by √2 (≈ 1.41).
Question
Is rms larger or smaller than the peak?
Answer
**Smaller** — rms = peak ÷ √2. The mains "230 V" is an **rms** value.
Question
What does a transformer do?
Answer
Changes an **AC voltage** up or down using two coils on a shared iron core.
Question
Transformer voltage and turns relationship?
Answer
$\dfrac{\varepsilon_p}{\varepsilon_s} = \dfrac{N_p}{N_s}$ — the **voltage ratio equals the turns ratio**.
Question
Step-up vs step-down transformer?
Answer
**Step-up**: more secondary turns ⇒ higher V, lower I. **Step-down**: fewer secondary turns ⇒ lower V, higher I.
Question
What does an ideal transformer conserve?
Answer
**Power**: $\varepsilon_p I_p = \varepsilon_s I_s$. That is why the **current ratio is inverted**.
Question
Find the secondary voltage of a transformer?
Answer
$V_s = V_p \times \dfrac{N_s}{N_p}$ — multiply the primary voltage by the turns ratio.
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Full study notes for Applications of electromagnetic induction
Topic 4.4 hub
Induction (HL)
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