Solid angle and its applications in Electrostatics

[@krishnamahara7478]

Very nice vedio on solid angle

[@sanjayvijayagiri3662]

Thank u sir

[@educhannel8188]

Thanks sir

[@kennethnavarro661]

Why is it theta equal to pi? I don't understand.

[@anirudhkanojia8803]

Oh nice, claps 👏🏻👏🏻

[@physicsdomain8548]

Thank you

[@laxmikumar9851]

Your lacture is so understand able. God bless you . I have a doubt Sir why we do dA=circumference× thickness Please remove my doubt.

[@physicsdomain8548]

To understand it, just cut an elementary strip from the sphere. It will be ring shaped strip. Now again cut this ring shaped circular strip and expand it on your plane table. You will find that it changes to a rectangle whose length will be equal to circumference of ring and breadth will be equal to thickness of elementary ring shaped strip. Now area of the strip will be equal to area of this newly formed rectangle. So dA= length of rectangle(circumference of strip) × breadth of rectangle (thickness of circular strip).

[@laxmikumar9851]

Thanks sir. My doubts is gone God bless you.

[@VIKASHKUMAR-nh4qm]

What is dA Please clear.

[@physicsdomain8548]

dA is the area of elementary strip shown in the figure.

[@physicsdomain8548]

When we apply formula 'solid angle = area/R^2', R is a fixed diatance from centre of curvature. So above formula holds for curved surface not for plane (for plane surface radius of curvature will be infinite). But solid angle will be the same for any area attached within the same boundary. This is the reason why we calculate the solid angle for cone by considering spherical surface(i.e. curved surface having radius of curvature R) not plane. Please reply whether it is clear or not! Thanks for watching!

[@VIKASHKUMAR-nh4qm]

@@physicsdomain8548 I think you are trying to say that for a plane surface solid angle cannot be defined and we are defining here solid angle by considering a small part of a sphere lying above the plane of base of cone.

[@VIKASHKUMAR-nh4qm]

Am I correct or not sir?

[@physicsdomain8548]

You are correct.

[@parthsharma2611]

It would be better if you increase your speed significance

[@physicsdomain8548]

Thank you for your valuable suggestions.