Consider each of the electric- and magnetic-field orientations given next. In each case, what is the direction of propagation of the wave? (a) E⃗ in the +x-direction, B⃗ in the +y-direction; (b) E⃗ in the -y-direction, B⃗ in the +x-direction; (c) E⃗ in the +z-direction, B⃗ in the -x-direction; (d) E⃗ in the +y-direction, B⃗ in the -z-direction.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg

elctricity and magnet is conversion to it

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m