TestUstad

A charged particle (q = 2 × 10⁻⁸ C, m = 4 × 10⁻⁶ kg) moves at 4 × 10³ m/s in a 0.1 T magnetic field at 30°. The radius of its helical path is:

Correct answer: C. 0.08 m

  • A. 0.02 m
  • B. 0.04 m
  • C. 0.08 m
  • D. 0.12 m

Explanation

Radius r = mv /(qB), where v = v sinθ = 4 × 10³ × sin 30° = 2 × 10³ m/s. Substituting m = 4 × 10⁻⁶ kg, q = 2 × 10⁻⁸ C, B = 0.1 T. r = (4 × 10⁻⁶ × 2 × 10³)/(2 × 10⁻⁸ × 0.1) = 0.08 m.

Written and checked by , contributorLast updated
Report an error

The more specific you are, the faster it gets fixed. A source beats an opinion.

Prefer email? [email protected]

About Electromagnetism

Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.

Practise Electromagnetism

1,176 free Electromagnetism MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.

Start a free Electromagnetism testAll Electromagnetism MCQs

Discussion

Stuck on an option, or know a faster way to get there? Ask or explain it here.

No comments yet. Be the first to explain this one.

Exams that ask Physics questions like this

Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.

Lecturer Physics Test Physics80 MCQsSubject Specialist Physics Test Physics80 MCQsNET Physics60 MCQsNUMS Physics40 MCQsDUHS Physics36 MCQsETEA MDCAT Physics36 MCQsKMU Physics36 MCQsMDCAT Physics36 MCQsECAT Physics30 MCQsETEA Engineering Admission Test Physics30 MCQsGIKI Physics30 MCQsNED Physics30 MCQsPIEAS Physics30 MCQsPMD Physics25 MCQsBSN Entry Test Physics20 MCQsPAF Airman Physics15 MCQs

More Electromagnetism questions

A circular coil of radius 0.1 m with 50 turns rotates at 1800 rpm in a 0.3 T magnetic field. The peak emf induced is:

A transformer with 500 primary turns and 100 secondary turns is connected to a 200 V AC supply. If the secondary delivers 5 A to a load, the primary current is:

A conducting rod of length 0.4 m moves at 5 m/s in a magnetic field of 0.2 T at 60° to the field. The motional emf induced is:

A solenoid of 1000 turns, length 0.8 m, and area 0.02 m² carries 3 A. The self-inductance of the solenoid is (μ₀ = 4π × 10⁻⁷ T·m/A):

A square loop of side 0.2 m moves at 10 m/s perpendicular to a 0.5 T magnetic field. If the loop's resistance is 5 Ω, the induced current is:

Four charges A, B, C, and D are shown here, moving with equal speeds in a uniform magnetic field. Which charge experiences the maximum force?