Magnetism and Moving Charges - AP Physics 2

1. What is the formula for the magnetic force on a moving charge?

   $F = qvB \, \sin(\theta)$. Force depends on charge, velocity, field strength, and angle between $v$ and $B$.

2. Identify the symbol for magnetic permeability of free space.

   $\mu_0$. Fundamental constant relating current to magnetic field in vacuum.

3. What is the effect of a magnetic field on a loop of current?

   Torque acts on the loop. Current loop behaves like magnetic dipole in external field.

4. What is the effect of a magnetic field on a stationary charge?

   No force is exerted. Magnetic force requires motion; stationary charges are unaffected.

5. State the right-hand rule for the direction of magnetic force.

   Thumb: velocity, Fingers: field, Palm: force. Use right hand to determine force direction on positive charges.

6. What does Lenz's Law state about electromagnetic induction?

   Induced current opposes the change causing it. Nature opposes changes in magnetic flux through circuits.

7. State the formula for the magnetic field inside a solenoid.

   $B = \mu_0 n I$. Field strength proportional to current and turns per unit length.

8. Define the term 'magnetic dipole moment'.

   Measure of the strength of a magnetic source. Quantifies the magnetic field strength produced by a current distribution.

9. What is the relationship between electric and magnetic fields in electromagnetic waves?

   Perpendicular to each other. EM waves consist of oscillating $E$ and $B$ fields at right angles.

10. State the Biot-Savart Law for the magnetic field due to a current element.

    $dB = \frac{\mu_0 I dl \sin(\theta)}{4\pi r^2}$. Fundamental law relating current elements to magnetic field production.

11. Identify the direction of the magnetic force on a negative charge.

    Opposite to the right-hand rule direction. Negative charges experience force opposite to positive charge direction.

12. Define Ampère's Law.

    Line integral of $B$ around a closed path equals $\mu_0 I$. Relates magnetic field circulation to enclosed current.

13. Calculate the magnetic field at a point $5cm$ from a wire carrying $6A$ current.

    $2.4 \times 10^{-5} \, T$. Using $B = \frac{\mu_0 I}{2\pi r}$ with given values.

14. State the formula for the magnetic field of a circular loop at its center.

    $B = \frac{\mu_0 I}{2R}$. Field at center is half that of an infinite straight wire.

15. What does a solenoid generate when a current flows through it?

    Uniform magnetic field inside. Coil of wire creates strong, uniform field along its axis.

16. What is the formula for the Lorentz force?

    $F = q(E + v \times B)$. Combines electric and magnetic forces on a moving charge.

17. What is the magnetic moment of a loop of current?

    $\mu = I \cdot A$. Product of current and loop area defines magnetic strength.

18. Identify the unit of magnetic flux.

    Weber (Wb). Named after Wilhelm Weber; unit of magnetic flux linkage.

19. Calculate the magnetic force on a $0.5C$ charge at rest in a $2T$ field.

    $0 \, N$. No velocity means no magnetic force on the charge.

20. State the relationship between current and magnetic field in a solenoid.

    Directly proportional. More current produces stronger magnetic field inside solenoid.

21. Define the unit of magnetic field strength.

    Tesla (T). Named after Nikola Tesla; measures magnetic field intensity.

22. State the effect of a uniform magnetic field on the speed of a charged particle.

    Speed remains constant. Magnetic force is perpendicular to velocity, doing no work.

23. What is the SI unit for electric charge?

    Coulomb (C). Fundamental unit for quantifying electric charge in physics.

24. Identify the direction of the magnetic moment vector of a current loop.

    Perpendicular to the plane of the loop. Vector points normal to loop plane using right-hand rule.

25. What is the path of a charged particle in a uniform magnetic field?

    Circular or helical. Magnetic force provides centripetal acceleration for curved motion.

26. What is the force between two parallel current-carrying wires?

    Attractive if currents are in the same direction. Parallel currents attract; antiparallel currents repel each other.

27. What is the Hall effect?

    Voltage developed across a conductor in a magnetic field. Moving charges in magnetic field separate, creating potential difference.

28. What is the direction of the magnetic field inside a solenoid?

    Parallel to the axis of the solenoid. Field lines run straight through the solenoid's center.

29. Calculate the magnetic force on a $3m$ wire carrying $5A$ in a $0.2T$ field.

    $3 \, N$. Using $F = ILB$: $5 \times 3 \times 0.2 = 3N$.

30. Define the term 'magnetic flux'.

    Product of magnetic field and area normal to it. Measures how much magnetic field passes through a surface.

31. State the formula for the magnetic force on a current-carrying wire.

    $F = ILB \sin(\theta)$. Force on wire depends on current, length, field, and orientation angle.

32. What is the value of $\mu_0$, the permeability of free space?

    $4\pi \times 10^{-7} \, T\cdot m/A$. Fundamental physical constant used in magnetic field calculations.

33. What is the direction of the magnetic field around a current-carrying wire?

    Circular around the wire. Right-hand rule: thumb along current, fingers curl with field.

34. Identify the condition for maximum magnetic force on a charge.

    $\theta = 90^{\circ}$. Perpendicular alignment gives maximum $\sin(\theta) = 1$.

35. What is the magnetic field formula for a long straight wire?

    $B = \frac{\mu_0 I}{2\pi r}$. Field strength decreases with distance; circular field lines around wire.

36. What is the formula for magnetic flux?

    $\Phi = B \cdot A \cdot \cos(\theta)$. Flux depends on field strength, area, and angle between them.

37. Find the magnetic force on a $2C$ charge moving at $3m/s$ in a $4T$ field at $90^{\circ}$.

    $24 \, N$. Using $F = qvB$: $2 \times 3 \times 4 = 24N$ at maximum angle.

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