NEET UG Physics Practice Paper – Magnetism & Moving Charges (Set 9)

Attempt all 30 MCQs and check your score instantly.

1. Magnetic force on charge is:

qvB sinθ
qE
mv²/r
IR

2. Unit of magnetic field:

Tesla
Volt
Ampere
Ohm

3. Direction of magnetic force:

Fleming left
Fleming right
Lenz law
Ohm law

4. Force on current carrying conductor:

BIL sinθ
qvB
IR
none

5. Motion of charge in uniform B (perpendicular):

circular
straight
random
none

6. Radius of circular motion:

mv/qB
qB/mv
mv²/qB
none

7. Cyclotron frequency:

qB/2πm
mv/qB
qE/m
none

8. Biot-Savart law gives:

magnetic field
electric field
force
voltage

9. Magnetic field around wire:

concentric circles
straight lines
radial
none

10. Ampere law relates:

B & current
E & charge
V & I
none

11. Magnetic field inside solenoid:

uniform
zero
infinite
none

12. Force between parallel currents:

attract
repel
none
zero

13. Torque on current loop:

NIBA
IR
V
none

14. Magnetic moment:

IA
IR
V
none

15. Earth acts like:

magnet
conductor
insulator
none

16. Magnetic dipole field varies as:

1/r³
1/r²
r
constant

17. Lorentz force:

q(E+v×B)
IR
mv²
none

18. Magnetic field unit:

Tesla
Volt
Joule
none

19. Right hand thumb rule gives:

direction of B
current
voltage
none

20. Magnetic field due to loop:

along axis
radial
zero
none

21. Torque on dipole:

MB sinθ
IR
qv
none

22. Magnetic lines form:

closed loops
open lines
straight
none

23. Magnetic field at center of loop:

μ₀I/2R
μ₀I/R
μ₀I/4R
none

24. Solenoid field:

μ₀nI
μ₀I
nI
none

25. Magnetic force does:

no work
work
infinite work
none

26. Cyclotron works on:

magnetic force
gravity
friction
none

27. Velocity selector uses:

E & B
only E
only B
none

28. Magnetic permeability unit:

H/m
Tesla
Volt
none

29. Magnetic susceptibility:

dimensionless
unit
Tesla
none

30. Diamagnetic materials:

weak repelled
attracted
strong attracted
none

Submit

NEET UG Physics Notes – Magnetism & Moving Charges (Set 9)

Magnetism and Moving Charges is a high-concept and moderately numerical chapter in NEET UG Physics. It combines ideas from electricity and motion, focusing on how moving charges create and experience magnetic fields.

---

1. Magnetic Force on Moving Charge

A charged particle moving in a magnetic field experiences a force.$$F = qvB \sin\theta$$F=qvBsinθ

Key Points:

• Force is maximum when $\theta = 90^\circ$θ=90∘
• Force is zero when motion is parallel to field
• Direction given by Fleming’s Left-Hand Rule

---

2. Lorentz Force

When both electric and magnetic fields are present:$$F = q(E + v \times B)$$F=q(E+v×B)

Understanding:

• Combines electric and magnetic forces
• Important in velocity selector and charged particle motion

---

3. Motion of Charged Particle in Magnetic Field

Case 1: Perpendicular Motion

• Circular path

$$r = \frac{mv}{qB}$$r=qBmv​$$T = \frac{2\pi m}{qB}$$T=qB2πm​

Case 2: At an Angle

• Helical path

Important Insight:

• Magnetic force does no work
• Only changes direction, not speed

---

4. Cyclotron

A device used to accelerate charged particles.

Cyclotron Frequency:

$$f = \frac{qB}{2\pi m}$$f=2πmqB​

Principle:

• Charged particle moves in circular path under magnetic field
• Electric field accelerates it

---

5. Magnetic Field Due to Current

Biot-Savart Law:

Gives magnetic field due to a current element.

Straight Wire:

$$B = \frac{\mu_0 I}{2\pi r}$$B=2πrμ0​I​

Circular Loop (Center):

$$B = \frac{\mu_0 I}{2R}$$B=2Rμ0​I​

---

6. Ampere’s Circuital Law

$$\oint B \cdot dl = \mu_0 I$$∮B⋅dl=μ0​I

Use:

• To find magnetic field in symmetric systems:
  • Solenoid
  • Toroid

---

7. Magnetic Field in Solenoid

$$B = \mu_0 n I$$B=μ0​nI

Where:

• $n$n = turns per unit length

Key Feature:

• Field inside is uniform
• Outside is nearly zero

---

8. Force Between Parallel Currents

• Same direction → Attraction
• Opposite direction → Repulsion

Formula:

$$F \propto \frac{I_1 I_2}{r}$$F∝rI1​I2​​

---

9. Magnetic Dipole

A current loop behaves like a magnetic dipole.

Magnetic Moment:

$$M = IA$$M=IA

Torque on Dipole:

$$\tau = MB \sin\theta$$τ=MBsinθ

---

10. Magnetic Field Lines

Properties:

• Form closed loops
• Outside magnet: North → South
• Inside magnet: South → North
• Never intersect

---

11. Earth’s Magnetism

• Earth behaves like a giant magnet
• Has magnetic poles different from geographic poles

Key Terms:

• Magnetic declination
• Magnetic inclination (dip)

---

12. Velocity Selector

Uses crossed electric and magnetic fields.

Condition for straight motion:

$$qE = qvB \Rightarrow v = \frac{E}{B}$$qE=qvB⇒v=BE​

---

13. Magnetic Materials

Diamagnetic:

• Weakly repelled
• Example: Bismuth

Paramagnetic:

• Weakly attracted

Ferromagnetic:

• Strongly attracted
• Example: Iron

---

14. Magnetic Permeability

$$\mu = \mu_0 \mu_r$$μ=μ0​μr​

Unit:

• Henry/m (H/m)

---

15. Magnetic Susceptibility

$$\chi = \frac{M}{H}$$χ=HM​

Key Point:

• Dimensionless quantity
• Indicates how material responds to magnetic field

---

16. Important NEET Concepts

Must Remember:

• $F = qvB \sin\theta$F=qvBsinθ
• $r = mv/qB$r=mv/qB
• $B = \mu_0 I / 2\pi r$B=μ0​I/2πr
• $B = \mu_0 n I$B=μ0​nI
• $\tau = MB \sin\theta$τ=MBsinθ

---

17. Common Mistakes

❌ Confusing electric force with magnetic force
❌ Forgetting magnetic force does no work
❌ Wrong direction using Fleming rule
❌ Mixing formulas of electric and magnetic fields

---

18. Quick Revision Tips

• Magnetic force changes direction, not speed
• Circular motion formula is frequently asked
• Solenoid and loop formulas are very important
• Focus on direction-based questions

---

Conclusion

Magnetism is a concept + formula-based chapter. NEET questions are mostly:

• Direct formula application
• Direction-based
• Conceptual

If you master:

• Lorentz force
• Circular motion
• Magnetic field formulas
• Current loops & solenoids

👉 You can score full marks easily in this chapter.