Plz =)

a student wishing to determine the cross sectional area of a wire takes a single reading of its diameter with a micrometer screw gauge and obtains a value of 0.19mm. he records the area of cross section as 0.02835 mm^2.assuming that his reading of the diameter is subjected to an uncertainty of 0.01mm, how should he write the result for the area?

An electromagnetic wave with frequency 65.0 hz travels in aninsulating magnetic material that has dielectric constant 3.64 andrelative permeability 5.18 at this frequency. the electric fieldhas amplitude 7.20 \times 10^{ - 3} {\rm v}/{\rm m}. a. what is the speed of propagation of the wave? b.what is the wavelength of the wave? c.what is the amplitude of the magnetic field? d.what is the intensity of the wave?

If you let go of the notebook after lifting it, will it move? how?

How do i solve this physics problem?