Magnetic fields, proving a magnetic field exists. PIS - Inelastic distortion, investigating elasticity, calc spring constant & energy transferred.

🧲 1. Magnetic Fields

🔹 Key Concepts

  • Magnetic field = region around a magnet where magnetic forces act

  • Field lines show:

    • Direction: North → South

    • Strength: Closer lines → stronger field

🔹 Proving a Magnetic Field Exists

  1. Using iron filings

    • Sprinkle filings around a magnet → they align along field lines

  2. Using a plotting compass

    • Place compass near magnet → needle aligns with field direction

  3. Observation

    • A small magnet can rotate or attract/repel another magnet or magnetic material

Key Tip: Magnetic field is invisible; field lines are a visual tool

⚡ 2. PIS – Physics of Inelasticity & Elasticity

🔹 Inelastic Distortion

  • Material is stretched beyond elastic limit → does not return to original shape

  • Energy is dissipated as heat or deformation, not stored

🔹 Investigating Elasticity (Hooke’s Law)

  • Hooke’s Law:

F=k×xF = k \times xF=k×x

  • FFF = force applied (N)

  • xxx = extension (m)

  • kkk = spring constant (N/m)

Practical Method:

  1. Hang weights on a spring

  2. Measure extension for each weight

  3. Plot force vs extension → straight line if elastic

  4. Calculate spring constant:

k=Fxk = \frac{F}{x}k=xF​

🔹 Energy Transferred (Elastic Potential Energy)

E=12kx2E = \frac{1}{2} k x^2E=21​kx2

  • EEE = energy stored (J)

  • kkk = spring constant (N/m)

  • xxx = extension (m)

Key Tip: Only applies within elastic limit

🔗 Big Links

  • Magnetic fields → invisible forces → shown with compass or iron filings

  • Inelastic vs elastic → elastic stores energy, inelastic loses energy

  • Hooke’s Law → linear relationship between force and extension

  • Energy stored → linked to spring constant and extension squared

⭐ Exam Tips

  • Draw magnetic field lines, label N → S

  • For elasticity, always check if material returns to original shape

  • Include units:

    • Force (N), extension (m), spring constant (N/m), energy (J)

  • Use graphs to find spring constant from slope