Exercice 1 Le télescope spati galaxie située à 4,75 x 1021 km
Donnée : 1 al = 946080000000
1) Calcule à combien d'anné
l'exemple, il faut faire un table
2) En déduire le temps qu'à mis
la lumière à arriver jusqu'au télescope ?

Suppose that an electromagnetic wave which is linearly polarized along the x−axis is propagating in vacuum along the z−axis. the wave is incident on a conductor which is placed at z > 0 region of the space. the conductor has conductivity σ, magnetic permeability µ and electric permittivity ε. (a) find the characteristic time for the free charge density which dissipates at the conductor. (b) write the maxwell equations and derive the wave equation for a plane wave propagating in a conductor. (c) find the attenuation distance at which the incident amplitude reduces to e ^−1 of its initial value. (d) find the electric and magnetic fields inside the conductor. 8 (e) find the power loss per area of the incident electromagnetic wave at the surface of conductor.

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid

Clothes dryer uses about 7 amps of current from a 240 volt line. how much power does it use?