'B' is the correct choice.
BUT ... the angle of incidence is not the angle between the light ray
and the mirror. It's the angle between the light ray and the NORMAL
to the mirror. The 'normal' is the line that's perpendicular to the mirror.
Delis cactus is the correct way to write it.
KE=1/2mv^2
KE=1/2 x 5kg x (10m/s)^2
KE= 2.5kg x 100m^2/s^2
KE= 250 J
Atomic mass is equal to the number of protons and neutrons. Electrons have so little mass that they are practically negligible.
Atomic mass= 4+4= 8 AMU
transformer makes use of mutual induction for its operation in which change in magnetic field in one coil due to variation of current , induces voltage in the other coil. so changing magnetic field in the primary coil is very much needed for the transformer. Alternating current is a current which varies with time , hence it is suitable to produce changing magnetic field in the primary coil. on the other hand , the direct current remains constant all the time. hence can not produce a changing magnetic field. so DC current is not useful for transformers.