Solved Numerical Problem No. 15.10 ( Unit-15: Electromagnetic Induction); HSSC-II (Class-12); Physics (Punjab Curriculum and Text Board, Lahore) With Verified Answers

Like any field, the Earth's magnetic field stores energy. Find the magnetic energy stored in a space where the strength of the earth's field is 7 ｘ10⁻⁵ T if the space occupies an area of 10 ｘ10⁸ m² and has a height of 750 m. (Answer: 1.46 ｘ10⁹ J). 

Data Given:

Magnetic field strength = B = 7 ｘ10⁻⁵ T

Area = A = 10 ｘ10⁸ m²  

Height = h = `\l` = 750 m

µ₀ = 4π ｘ10⁻⁷ Wb A⁻¹ m⁻¹

To Find:

Magnetic Energy stored in space = `\U_m` = ?

Solution:

The relation for the required Magnetic Energy is

`\U_m` = `\frac {1}{2}` `\frac {B^2}{μ_0}` `\Al`

Putting the corresponding values 

`\U_m` = `\frac {1}{2}` `\frac {(7 ｘ10⁻⁵ T)^2}{4 ｘ 3.1416 ｘ10⁻⁷ Wb A⁻¹ m⁻¹}` ｘ 10 ｘ10⁸ m² ｘ 750 m

`\U_m` = `\frac {1}{2}` ｘ`\frac {49 ｘ10⁻⁻¹⁰ T^2}{12.5664 ｘ10⁻⁷ Wb A⁻¹ m⁻¹}` ｘ 7500 ｘ10⁸ m³

`\U_m` = `\frac {1 ｘ 49 ｘ10⁻¹⁰ T^2 ｘ 7500 ｘ10⁸ m³}{2 ｘ 12.5664 ｘ10⁻⁷ Wb A⁻¹ m⁻¹}`

`\U_m` = `\frac {367500 ｘ10⁻² T^2 m³}{25.1328 ｘ10⁻⁷ Wb A⁻¹ m⁻¹}`

or

`\U_m` = 14622.326 ｘ10⁵ J

or

`\U_m` = 1462.233 ｘ10⁶ J

or

`\U_m` = 1.462 ｘ10⁹ J ---------------Ans.

************************************

Shortcut Links For 

1. National MDCAT, ECAT, JOB EXAM Physics MCQs Preparation (New) 
2. Physics (New) 11th Class SLO Based Notes
3. Physics (New) 11th class MCQs Quizzes All Units
4. Physics (New) 12th Class SLO Based Notes
5. Physics (New) 12th class MCQs Quizzes All Units

1. Website for School and College Level Physics   

(https://askrarequiz.blogspot.com)

2. Website for School and College Level Mathematics  

(https://askraremaths.blogspot.com)

3. Website for Single National Curriculum Pakistan - All Subjects Notes 

(https://askrareclassnotes.blogspot.com/)

© 2022-Onwards by Academic Skills and Knowledge (ASK)     

Note:  Write me in the comment box below for any query and also Share this information with your class-fellows and friends.