1. What is Moving Charges and Magnetism?

It’s the study of magnetic fields created by moving electric charges and their interaction with other moving charges or currents.

GenZ Example

Current in headphone wire makes it magnetic near a compass needle.

2. Important AAI ATC Focused Concepts

3. Magnetic Force on a Moving Charge

The force experienced by a charged particle moving in a magnetic field.

\( F = q (v \times B) \) or \( F = q v B \sin\theta \)

Where:

F: Force (N)
q: Charge (C)
v: Velocity (m/s)
B: Magnetic field (T)
θ: Angle between v and B

PYQ Type: Formula/units MCQ

4. Lorentz Force (when both electric and magnetic fields act)

The total force on a charged particle in combined electric and magnetic fields.

\( \vec{F} = q (\vec{E} + \vec{v} \times \vec{B}) \)

Where:

E: Electric field

5. Force on Current-Carrying Conductor

The force on a conductor carrying current in a magnetic field.

\( F = I L B \sin\theta \)

Where:

I: Current (A)
L: Length of conductor (m)
B: Magnetic field (T)

GenZ Example

Fan motor works because current interacts with magnetic field.

6. Magnetic Field at Center of Circular Coil

The magnetic field produced at the center of a circular coil carrying current.

\( B = \frac{\mu_0 I}{2R} \)

Where:

μ₀: \( 4\pi \times 10^{-7} \, Tm/A \)

PYQ Type: Unit match/definition

7. Right-Hand Thumb Rule

Rule to determine the direction of magnetic field lines.

Thumb: Current direction
Curled fingers: Magnetic field lines direction

AAI ATC Concept MCQ

8. Ampere’s Circuital Law

Used to calculate magnetic fields around conductors.

\( \oint \vec{B} \cdot d\vec{l} = \mu_0 I \)

9. AAI ATC PYQ Analysis (2021–2023)

2021 Shift 2: Unit of magnetic field (Tesla)

2022 Shift 3: Right-hand thumb rule direction MCQ

2023 Feb Shift 1: Force on moving charge formula MCQ

10. Moving Charges & Magnetism Formula Quick Revision

Formula	Meaning
\( F = q v B \sin\theta \)	Magnetic force on moving charge
\( F = I L B \sin\theta \)	Force on current carrying wire
\( B = \frac{\mu_0 I}{2R} \)	Magnetic field at center of coil
\( \vec{F} = q (\vec{E} + \vec{v} \times \vec{B}) \)	Lorentz force

11. Quick Concept Recap

Concept	GenZ Example
Moving charge produces magnetic field	Charging cable disturbs compass
Right-hand thumb rule	Current = thumb, field = curled fingers
Fan motor	Current wire + magnetic field produces motion

12. Final AAI ATC Takeaway

Focus Areas:

1–2 questions per shift
Magnetic force formula
Lorentz force
Right-hand thumb rule application
Unit of Tesla
Magnetic field in coil

13. 10-Question AAI ATC-Style MCQ Mock Test — Moving Charges & Magnetism

Q1. The unit of magnetic field strength is:
a) Tesla
b) Ampere
c) Henry
d) Volt
Ans: a

Q2. Formula for force on a moving charge in a magnetic field is:
a) q E
b) q v B sinθ
c) I L B
d) q B / v
Ans: b

Q3. Right-hand thumb rule is used to determine:
a) Force on moving charge
b) Magnetic field around conductor
c) Electric force
d) None
Ans: b

Q4. What is the SI unit of magnetic permeability (μ₀)?
a) Tm/A
b) N/C
c) Wb
d) A/m
Ans: a

Q5. Magnetic field at center of a coil is directly proportional to:
a) I
b) R
c) 1/I
d) 1/R²
Ans: a

Q6. Lorentz force includes:
a) Magnetic force only
b) Electric force only
c) Both Electric and Magnetic
d) None
Ans: c

Q7. Force experienced by a stationary charge in a magnetic field is:
a) Maximum
b) Zero
c) Infinite
d) Can’t say
Ans: b

Q8. A positive charge moves perpendicular to a magnetic field, the path is:
a) Circular
b) Rectilinear
c) Spiral
d) Parabolic
Ans: a

Q9. Formula for force on a conductor carrying current in a magnetic field:
a) q v B
b) I L B sinθ
c) q B / E
d) I² B L
Ans: b

Q10. What happens to force when angle between v and B is 0°?
a) Maximum
b) Zero
c) Minimum
d) Infinite
Ans: b