Question

A closely wound solenoid `80cm` long has layers of windings of `400 turns` each. The diameter of the solenoid is `1*8cm`. If the current carried is `8*0A` estimate the magnitude of `vecB` inside the solenoid near its centre.
A. `1.5 xx10^(-2)T` opposite to the axis of solenoid
B. `2.5 xx10^(-2)T` along the axis of solenoid
C. `3.5 xx10^(-2)T` along the axis fo solenoid
D. `1.5 xx10^(-2)T` opposite to the axis of solenoid

Answer 1

Correct Answer - B
The length of solenoid I =80 cm =0.08 m
Number of layers =5
Number of turns per layer =400
Diamter of solenoid =1.8 cm
current in solenoid I =8A
`therefore` The total number of turns `N=4005=2000`
and number of turns / length `n=(2000)/(0.8)=2500`
The magnitude of magnetic field inside th solenoid
`B=mu_(0)nI =4xx3.14xx10^(-7)xx2500xx8=2.5xx10^(-2)T`
The direction of magnetic field is along the axis of solenoid