Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

Theme D — Fields

D.2 Electric and Magnetic Fields — IB Physics SL Revision Notes & Topical Questions

5 min read 11 parts Lesson 7 of 21 1 quiz

📚 IB Physics SL Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
0%read
Lesson summary

D.2 Electric and Magnetic Fields — IB PHYSICS SL notes: Describe electric charge and its conservation, apply Coulomb's law and electric field strength, and describe the magnetic fields of magnets and currents.Quantisation — charge comes in units of e = 1.60 × 10−19 CConservation …

  • By friction
  • By contact
  • By electrostatic induction
  • Comparison with gravity
  • Point charge
  • Parallel plates

Part 1 of 8Charge

Charge
Quantisation
  • Quantisation charge comes in units of e = 1.60 × 10−19 C
Conservation
  • Conservation in any process the total charge is conserved
Two types
  • Two types like charges repel and unlike charges attract

Part 2 of 8Charging

Charging
By friction
  • By friction electrons are transferred
By contact
  • By contact charge is shared
By electrostatic induction
  • By electrostatic induction charge is separated without contact

Part 3 of 8Coulomb's law

Coulomb's law
  • Coulomb's law the force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation
  • F = kq1q2/r2 in a vacuum, with k = 1/4πε0 = 8.99 × 109 N m2 C−2.
Comparison with gravity
  • Comparison with gravity it has the same inverse-square form
  • It may be attractive or repulsive.
  • It is far stronger for elementary particles.

Part 4 of 8Electric field strength

Electric field strength
  • Electric field strength the force per unit positive test charge, E = F/q
    What the symbols mean: E = electric field strength (N C−1) · F = force on the charge (N) · Q or q = charge (C)
  • Its unit is N C−1 or V m−1.
  • It is a vector in the direction of the force on a positive test charge.
Point charge
  • E = kQ/r2
Parallel plates
  • Parallel plates the field is uniform with E = V/d

Part 5 of 8Electric field patterns

Point charge
  • Point charge lines are radial outward from a positive charge and inward to a negative one
Parallel plates
  • Parallel plates lines are parallel and equally spaced, bulging slightly at the edges
Rules
  • Rules lines run from positive to negative, never cross and meet conductors at right angles

Part 6 of 8Magnetic fields

Magnetic field
  • Magnetic field a region in which a moving charge, current or magnetic pole experiences a force
Direction
  • Direction it is the direction of the force on a north pole
Magnets
  • Magnets field lines run from north to south outside a magnet and form closed loops
Straight wire
  • Straight wire field lines are concentric circles, with direction from the right-hand grip rule
    • (thumb along the current)
Solenoid
  • Solenoid the field is nearly uniform inside and like a bar magnet outside

Part 7 of 8Combining electric fields

1
Mark the charges and the point of interest.
2
Calculate the field or force from each charge separately.
3
Assign directions, away from positive and towards negative.
4
Add the contributions as vectors.

Part 8 of 8Gravitational and electric fields compared

FeatureGravitationalElectric
Acts onMassCharge
Force lawGm1m2/r2kq1q2/r2
DirectionAttractive onlyAttractive or repulsive
Field strengthForce per unit massForce per unit charge
Can be shielded?NoYes

Key terms

TermMeaning
Coulomb's lawThe force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation.
Electric field strengthThe force per unit positive test charge.
Conservation of chargeThe total charge of an isolated system is constant.
Quantisation of chargeCharge exists only in whole-number multiples of the elementary charge e.
Magnetic fieldA region in which a moving charge, current or magnetic pole experiences a force.
SolenoidA long coil of wire that produces a nearly uniform magnetic field inside when it carries a current.

Avoid these mistakes

Avoid these mistakes
Believing a charged object has gained protons — electrons are transferred.
Reversing the direction of the force on a negative charge.
Forgetting that magnetic field lines form closed loops.

Last updated:

Transformer Golden Equations Physics Standard

Transformer Turns Ratio & Efficiency

Ratio: Vp / Vs = Np / Ns = Is / Ip

  • Step-up reduces grid thermal loss (P = I2R).
  • Laminated core prevents eddy currents.
\n