In a young's double-slit experiment, the angle that locates the second dark fringe on either side of the central bright fringe is 6.5 degrees. find the ratio d/λ of the slit separation d to the wavelength λ of the light.

(d/λ) = 17.67

Explanation:

Equation for double-slit:

d*sinθ = m*λ

Rearrange the equation

(d/λ) = m/(sinθ)

Since it is at the second dark fringe, m = 2

Therefore:

(d/λ) = 2/(sin(6.5)

(d/λ) = 17.67

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg

because if the tool that you are using is not balanced it there would be false mass.