What is the displacement variable in a simple pendulum and the propagation of light?

The ratio of the magnitude of the magnetic field $(B_0)$ and electric field intensity $(E_0)$ of a plane electromagnetic wave in free space with permeability $\mu_0$ and permittivity $\varepsilon_0$ is (Given that $c$ is the velocity of light in free space):

$A$ lamp emits monochromatic green light uniformly in all directions. The lamp is $3\%$ efficient in converting electrical power to electromagnetic waves and consumes $100\,W$ of power. The amplitude of the electric field associated with the electromagnetic radiation at a distance of $10\,m$ from the lamp will be........$V/m$

If a $10 \ W$ bulb emits electromagnetic waves uniformly in all directions,then the intensity of light at a distance $0.5 \ m$ from the source is nearly (in $W \ m^{-2}$)

An electromagnetic wave with frequency $\omega$ and wavelength $\lambda$ travels in the $+y$ direction. Its magnetic field is along the $+x$ axis. The vector equation for the associated electric field (of amplitude $E_0$) is:

$A$ laser beam has intensity $17.7 \times 10^{14} \ W/m^2$. The amplitude of the electric field is
[Use $\epsilon_0 = 8.85 \times 10^{-12} \ C^2 / (N \cdot m^2)$]