Question

Why electric field strength and work done is scalar quantity?

Answer 1

A scalar quantity is that which it doesn't matter about the direction of the quantity. Speed is scalar, so it doesn't matter which direction it is moving. Velocity is a vector, so the direction matters.

Work doesn't matter which direction it is being used, since it wouldn't make much sense to do work to move something, use more work to move it back then say as work is a scalar quantity no work has been done.

I guess another way of describing it is that scalar quantities don't care how far you have gone to measure the variable.Actually electric field is the region around an
electric charge in which it exerts force on other charges. Being a region in space it is scalar quantity.