The speed of electromagnetic waves is the same for all ........

In a plane electromagnetic wave,the average value of ....... is zero.

About $5 \%$ of the power of a $100 \; W$ light bulb is converted to visible radiation. What is the average intensity of visible radiation
$(a)$ at a distance of $1 \; m$ from the bulb?
$(b)$ at a distance of $10 \; m$? Assume that the radiation is emitted isotropically and neglect reflection.

This question has Statement-$1$ and Statement-$2$. Of the four choices given after the statements,choose the one that best describes the two statements.
Statement-$1$: Out of radio waves and microwaves,the radio waves undergo more diffraction.
Statement-$2$: Radio waves have a greater frequency compared to microwaves.

$A$ beam of light travelling along the $X$-axis is described by the electric field $E_{y} = 900 \sin \omega(t - x/c)$. The ratio of the electric force to the magnetic force on a charge $q$ moving along the $Y$-axis with a speed of $3 \times 10^{7} \, m/s$ will be:
[Given: speed of light $c = 3 \times 10^{8} \, m/s$]

The electromagnetic waves travel in a medium at a speed of $2.0 \times 10^{8} \ m/s$. The relative permeability of the medium is $1.0$. The relative permittivity of the medium will be (in $.25$)