# A closely wound solenoid 80 cm long has 5 layers of windings of 400 turns each. The diameter of the solenoid is 1.8 cm. If the current carried is 8.0 A, - Physics

Numerical

A closely wound solenoid 80 cm long has 5 layers of windings of 400 turns each. The diameter of the solenoid is 1.8 cm. If the current carried is 8.0 A, estimate the magnitude of B inside the solenoid near its centre.

#### Solution

Length of the solenoid, l = 80 cm = 0.8 m

There are five layers of windings of 400 turns each on the solenoid.

∴ Total number of turns on the solenoid, N = 5 × 400 = 2000

Diameter of the solenoid, D = 1.8 cm = 0.018 m

Current carried by the solenoid, I = 8.0 A

Magnitude of the magnetic field inside the solenoid near its centre is given by the relation,

B = (mu_0"NI")/"l"

Where,

mu_0 = Permeability of free space = 4π × 10–7 T m A–1

B = (4pi xx 10^-7 xx 2000 xx 8)/(0.8)

= 8π × 10–3

= 2.512 × 10–2 T

Hence, the magnitude of the magnetic field inside the solenoid near its centre is 2.512 × 10–2 T.

Concept: Magnetic Field on the Axis of a Circular Current Loop
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#### APPEARS IN

NCERT Class 12 Physics Textbook
Chapter 4 Moving Charges and Magnetism
Q 8 | Page 169
NCERT Physics Part 1 and 2 Class 12
Chapter 4 Moving Charges and Magnetism
Exercise | Q 4.8 | Page 169