Question 8 Which of the following statements is true? (a) A convex lens has 4 dioptre power having a focal length 0.25 m. (b) A convex lens has -4 dioptre power having a focal length -0.25 m. (c) A concave lens has 4 dioptre power having a focal length 0.25 m. (d) A concave lens has 4 dioptre power having a focal length -0.25 m.
If 614% of a weight is 0.25kg. What is 45% of this weight?
A wire of 10−3cm2 cross sectional area carries a current of 0.25 A, then current density is