A9 × 1014 hz laser emits a 8.8 μs pulse, 5.0 mm in diameter, with a beam energy density of 0.8 j/m3. the number of wavelengths in the length of the beam is closest to?

To solve this problem we will apply the concepts related to Frequency (Reverse to Period) and the description of the wavelength as a function of the speed of light at the rate of frequency.

Our Laser frequency is given as

Therefore the laser wavelength would be

Where,

c = Speed of light

f = Frequency

The laser pulse is emitted at a period (T) of

Therefore the pulse wavelength would be

Finally the number of wavelengths is the ratio between the two wavelengths, then

The number of wavelengths in the beam length is closer to

the tires are rotating at 0.434 rpmlinear speed=45 m/sdiameter=0.550 mradius=0.275 mnow v= rωω= v/rω=45/0.275ω=163.6 rad/sω=163.6 rad/s (1rev/2π rad) (60s/1m)ω=1563 rpm