Exams › NEET › Physics
A wire carries a current. Maintaining the same current it is bent first to form a circular plane coil of one turn which produces a magnetic field B at the centre of the coil. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre of the double loop, caused by the same current is
- 4B
- B/4
- B/2
- 2B
Correct answer: 4B
Solution
The magnetic field at the center of a circular coil is directly proportional to the number of turns squared and inversely proportional to the radius. When the wire is bent into a double loop, the number of turns doubles, and the radius becomes half. This results in a magnetic field that is 4 times the original field, B.
Related NEET Physics questions
- An alternating electric field, of frequency ν, is applied across the dees (radius = R) of a cyclotron that is being used to accelerate protons (mass = m). The operating magnetic field (B) used in the cyclotron and the kinetic energy (K) of the proton beam, produced by it, are given by:
- A proton carrying 1 MeV kinetic energy is moving in a circular path of radius R in uniform magnetic field. What should be the energy of an α-particle to describe a circle of same radius in the same field?
- A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. The particle will
- An electron enters a region where magnetic field (\( \vec{B} \)) and electric field (\( \vec{E} \)) are mutually perpendicular, then
- A \( 10 \, \text{eV} \) electron is circulating in a plane at right angles to a uniform field at magnetic induction \( 10^{-4} \, \text{Wb/m}^2 \) (\( = 1.0 \, \text{gauss} \)). The orbital radius of the electron is
- A uniform magnetic field acts at right angles to the direction of motion of an electron. As a result, the electron moves in a circular path of radius \( 2 \, \text{cm} \). If the speed of electron is doubled, then the radius of the circular path will be
⚔️ Practice NEET Physics free + battle 1v1 →