Exams › NEET › Physics
Two circular coils 1 and 2 are made from the same wire but the radius of the 1st coil is twice that of the 2nd coil. What potential difference in volts should be applied across them so that the magnetic field at their centres is the same?
- 4
- 6
- 2
- 3
Correct answer: 2
Solution
The magnetic field at the center of a circular coil is proportional to the current and inversely proportional to the radius. Since the radius of the first coil is twice that of the second, the current in the first coil must be halved to produce the same magnetic field. As resistance is proportional to the length of the wire (and hence radius), the potential difference across the first coil must also be halved. Thus, the ratio of potential differences is 2:1, and the answer is 2.
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 →