JEE Main2012PhysicsCapacitanceActual
This question has Statement 1 and Statement 2 . Of the four choices given after the Statements, choose the one that best describes the two Statements. Statement 1: It is not possible to make a sphere of capacity 1 farad using a conducting material. Statement 2: It is possible for earth as its radius is 6.4 10^6 ~m .
Options
- AStatement 1 is true, Statement 2 is true, Statement 2 is the correct explanation of Statement 1.
- BStatement 1 is false, Statement 2 is true.
- CStatement 1 is true, Statement 2 is true, Statement 2 is not the correct explanation of Statement 1.
- DStatement 1 is true, Statement 2 is false.
Correct answer
D. Statement 1 is true, Statement 2 is false.
Step-by-step solution
Capacitance of sphere is given by: C=4 ₀ r If, C=1 ~F then radius of sphere needed: r= C 4 ₀ = 1 4 8.85 10⁻¹² or, r= 10¹² 4 8.85 =9 10^9 ~m 9 10^9 ~m is very large, it is not possible to obtain such a large sphere. Infact earth has radius 6.4 10^6 ~m only and capacitance of earth is 711 F .