Very short pulses of high-intensity laser beams are used to repair detached portions of the retina of the eye. the brief pulses of energy absorbed by the retina welds the detached portion back into place. in one such procedure, a laser beam has a wavelength of 810 nm and delivers 250 mw of power spread over a circular spot 510 μm in diameter. the vitreous humor (the transparent fluid that fills most of the eye) has an index of refraction of 1.34.

a) if the laser pulses are each 1.50 ms long, how much energy is delivered to the retina with each pulse? express your answer with the appropriate units
b) what average pressure would the pulse of the laser beam exert at normal incidence on a surface in air if the beam is fully absorbed? express your answer with the appropriate units.
c) what are the wavelength of the laser light inside the vitreous humor of the eye? express your answer with the appropriate units.
d) what is the frequency of the laser light inside the vitreous humor of the eye? express your answer with the appropriate units.
e) what is the maximum value of the electric field in the laser beam? express your answer with the appropriate units.
f) what is the maximum value of the magnetic field in the laser beam?

Describe the path of a ray that approaches a mirror parallel to the principal axis.

How are calculation for velocity and speed different

Dinate system, and a charge q = - 2.00 nc is placed s2 10 n> c. (a) what is the change in electric potential energy when the dipole moment of a molecule changes its orientation with respect to es from parallel to perpendicular? (b) at what absolute temperature t is the average translational kinetic energy 32 kt of a molecule equal to the change in potential energy calculated in part(: abovethistemperature,thermalagitationprevents the dipoles from aligning with the electric field.) placed in a uniform electric field e with magnitude 1.6 * 6 on the positive x-axis at x = 4.00 cm. (a) if a third charge q3 = +6.00 nc is now placed at the point x = 4.00 cm, y = 3.00 cm, find the x- and y-components of the total force exerted on this charge by the other two. (b) find the magnitude and direction of figure p21.62 ll uu 21.55 . torque on a dipole. an electric dipole with dipole moment ps is in a uniform external electric field es. (a) find the orientations of the dipole for which the torque on the dipole is zero. (b) which of the orientations in part (a) is stable, and which is unstable? (hint: consider a small rotation away from the equi- librium position and see what happens.) (c) show that for the stable orientation in part (b), the dipole’s own electric field tends to oppose the external field. 21.62 ..