A machine has 800 J of input work and 200 J of output work. What is the machine's efficiency? A 2%

B 25%

C 40%

D 1000%

Find an expression for the electric field e⃗ at the center of the semicircle. hint: a small piece of arc length δs spans a small angle δθ=δs /r, where r is the radius. express your answer in terms of the variables q, l, unit vectors i^, j^, and appropriate constants.