Advertisements
Advertisements
Question
In what respect is a toroid different from a solenoid?
Advertisements
Solution
Toroid
• It is a hollow circular ring on which a large number of turns of a wire are closely wound.
• Three Amperian loops (1, 2, and 3) are shown by dotted lines.
• Magnetic field along loop 1 is zero because the loop encloses no current.
• Magnetic field along loop 3 is zero because the current coming out of the paper is cancelled exactly by the current going out of it.
• Magnetic field at S (along loop 2):
From Ampere’s law,
∴B (2πr) = μ0NI
Where,
B → Magnetic field
r → Radius
I → Current
N → Number of turns of toroidal coil
`therefore B=(mu_0NI)/(2pir)`
APPEARS IN
RELATED QUESTIONS
Use this law to obtain the expression for the magnetic field inside an air cored toroid of average radius 'r', having 'n' turns per unit length and carrying a steady current I.
Derive an expression for the mutual inductance of two long co-axial solenoids of same length wound one over the other,
Obtain the expression for mutual inductance of a pair of long coaxial solenoids each of length l and radii r1 and r2 (r2 >> r1). Total number of turns in the two solenoids are N1 and N2, respectively.
Define self-inductance of a coil.
Obtain the expression for the magnetic energy stored in an inductor of self-inductance L to build up a current I through it.
Draw and compare the pattern of the magnetic field lines in the two cases ?
The magnetic field B inside a long solenoid, carrying a current of 5.00 A, is 3.14 × 10−2 T. Find the number of turns per unit length of the solenoid.
A long solenoid is fabricated by closely winding a wire of radius 0.5 mm over a cylindrical nonmagnetic frame so that the successive turns nearly touch each other. What would be the magnetic field B at the centre of the solenoid if it carries a current of 5 A?
A tightly-wound, long solenoid carries a current of 2.00 A. An electron is found to execute a uniform circular motion inside the solenoid with a frequency of 1.00 × 108 rev s−1. Find the number of turns per metre in the solenoid.
A tightly-wound, long solenoid is kept with its axis parallel to a large metal sheet carrying a surface current. The surface current through a width dl of the sheet is Kdl and the number of turns per unit length of the solenoid is n. The magnetic field near the centre of the solenoid is found to be zero. (a) Find the current in the solenoid. (b) If the solenoid is rotated to make its axis perpendicular to the metal sheet, what would be the magnitude of the magnetic field near its centre?
