Question

Investigators measure the size of fog droplets using the diffraction of light. A camera records the diffraction pattern on a screen as the droplets pass in front of a laser, and a measurement of the size of the central maximum gives the droplet size. In one test, a 690 nm laser creates a pattern on a screen 30 cm from the droplets. If the central maximum of the pattern is 0.24 cm in diameter, how large is the droplet?

Answer 1

the diameter of the droplet is 0.021045 cm or 2.1 × 10⁻² cm

Step-by-step explanation:

Given the data in the question;

Diameter of bright central maxima;

⇒ 2 × ( 1.22 × (λD/d) ) ⇒ 2.44( λD/d )

where D is the distance from the the droplet to the screen ( 30 cm )

d is the diameter of the droplet

λ is the wavelength of light ( 690 nm = 690 × 10⁻⁷ cm )

since the central maximum of the pattern is 0.24 cm in diameter,

we substitute

0.24 cm = 2.44( ( 690 × 10⁻⁷ cm × 30 cm ) / d )

solve for d

d = 2.44( ( 690 × 10⁻⁷ cm × 30 cm ) / 0.24 cm

d = 0.0050508 cm² / 0.24 cm

d = 0.021045 cm or 2.1 × 10⁻² cm

Therefore, the diameter of the droplet is 0.021045 cm or 2.1 × 10⁻² cm