The nuclear forces

a. are central forces, independent of the spin of the nucleons.

b. have a short-range dominant over a distance of about a few fermi

c. are stronger being hundred times stronger than that of electromagnetic forces.

d. are independent of the nuclear charge.

Which of the above is not true?

Two light rays A and B travel from a medium into air at angles of incidence 15 degrees and 42 degrees respectively. In the medium, light travels 3 cm in 0.2 ns . Will there be total internal reflection? If so, which ray?

An electric field $E=3 x^2 i N C^{-1}$ exists in a certain region of space. The potential difference between the origin and at $x=4 m, V_0-V_4$ is

A symmetric double convex lens is cut into two equal parts by a plane perpendicular to the principal axis. If the power of the original lens is 4D, the difference between the powers of the original lens and the cut lens is