IPhO 2019 — Teorica — A2

Italiano (Italy)

Theory A2-1 Italiano (Italy) La fisica di un forno a microonde - Foglio risposte Parte A: La struttura e il funzionamento di un magnetron (6.6 punti) A.1 (0.4 pt)

$f_{\text{est}}=$ A.2 (1.5 pt)

1. Per $\vec{u}(0)=(3E_0/B_0)\hat{x}$, si ha ${\vec{u}}_D=$

2. Per $\vec{u}(0)=-(3E_0/B_0)\hat{x}$, si ha ${\vec{u}}_D=$

A.3 (0.4 pt)

$r=$

Theory A2-2 Italiano (Italy) A.4 (1.2 pt) punto verso l’anodo verso il catodo perpendicolare al raggio A B C D E A.5 (1.2 pt) punti l’angolo diminuisce l’angolo aumenta variazione indeterminata AB BC CA DE EF DF

Theory A2-3 Italiano (Italy) A.6 (0.8 pt) ${\omega }_s=$ A.7 (1.1 pt)

$V_0=$ Parte B: L’interazione della radiazione a microonde con le molecole d’acqua (3.4 punti)

Theory A2-4 Italiano (Italy) B.1 (0.5 pt)

$\tau (t)=$

$H_i(t)=$ B.2 (0.5 pt)

$⟨H(t)⟩=$ B.3 (1.1 pt)

$I(z)=$ B.4 (0.6 pt)

$\beta =$ B.5 (0.7 pt) $z_{1/2}=$ materiale $z_{1/2}$ aumenta con la temp. $z_{1/2}$ diminuisce con la temp. $z_{1/2}$ resta invariato acqua zuppa

Topic: Electromagnetism, Magnetism, Oscillations & Waves Metodi: Lorentz Force Analysis, Simple Harmonic Motion Analysis, Physical Modeling Competenze: Mathematical Modeling, Physical Reasoning, Diagrammatic Reasoning Objects: — Fonte: Testo (PDF) — p.1 Soluzione: Soluzioni (PDF)

English (United States)

Theory A2-1 English (United States) The physics of a microwave oven – Answer sheet Part A: The structure and operation of a magnetron (6.6 points)

A.1 (0.4 pt) $f_{\text{est}}=$

A.2 (1.5 pt)

1. For $\vec{u}(0)=(3E_0/B_0)\hat{x}$, one obtains ${\vec{u}}_D=$

2. For $\vec{u}(0)=-(3E_0/B_0)\hat{x}$, one obtains ${\vec{u}}_D=$

A.3 (0.4 pt) $r=$

Theory A2-2 English (United States) A.4 (1.2 pt) direction toward the anode toward the cathode perpendicular to the radius A B C D E

A.5 (1.2 pt) points the angle decreases the angle increases indeterminate change AB BC CA DE EF DF

Theory A2-3 English (United States) A.6 (0.8 pt) ${\omega }_s=$

A.7 (1.1 pt) $V_0=$

Part B: The interaction of microwave radiation with water molecules (3.4 points)

Theory A2-4 English (United States) B.1 (0.5 pt) $\tau (t)=$ $H_i(t)=$

B.2 (0.5 pt) $⟨H(t)⟩=$

B.3 (1.1 pt) $I(z)=$

B.4 (0.6 pt) $\beta =$

B.5 (0.7 pt) $z_{1/2}=$ material $z_{1/2}$ increases with temperature $z_{1/2}$ decreases with temperature $z_{1/2}$ remains unchanged water soup

Solution: Soluzioni (PDF)