prove displacement of a body in nth second is given by the S=u+a/2(2n-1) where symbols have their usual meaning

1 answer:

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The proof that the displacement of a body in nth second which is given by the S=u+a/2(2n-1) is explained below.

<h3>Calculations and Parameters</h3>

Given:

u= initial velocity
a= acceleration

Displacement during nth second= displacement in n seconds- displacement in (n-1) seconds

= [ $un + \frac{1}{2} gn^2] - [ u(n-1) + \frac{1}{2} g(n-1)^2]$

= (u * 1) + g(n *1) - $\frac{g}{2}$ (1 *1)

Hence, in (n-1) seconds, n has a unit of time and 1 has a unit of time (not a constant)

Therefore, u(m/s) is multiplied by 1 (unit of time)

g(m/s^2) is multiplied by ( n*1 ), having units of time, i.e s^2

g/2 is also multiplied by ( 1 * 1, also having units of time, i.e s^2

Therefore, the equation is dimensionally correct and we should note that 1 is not a constant in the equation as the time of 1 second in (n-1) second.

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Because the top mirror is not perfectly reflective (it reflects 90% of the photons, allowing 10% of them to go through), the pow

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This question is incomplete, the complete question;

you make an interferometer using 50-50 beam splitter and two mirrors, one being a perfect mirror and one which does not reflect all light. The wavelength of the 9 mW incident laser is 400 nm.

Because the top mirror is not perfectly reflective (it reflects 90% of the photons, allowing 10% of them to go through), the power measured at the detector when only the vertical arm is blocked is 2.25 mW, while the power measured at the detector when only the horizontal arm is blocked is only 2.025 mW. Assume initially the intensity is at its maximum. How much would we need to translate the perfect mirror to the right to get a minimum intensity at detector, and what is that minimum intensity

Options;

a) 200 nm; 0.9 mW

b) 100 nm, 0.0059 mW

c) 200 nm; 0 mW

d) 100 nm; 0.9 mW

e) 200 nm; 0.0059 mW

Answer:

the amount we need to translate the perfect mirror to the right to get a minimum intensity at detector and the minimum intensity are;

100 nm; 0.0059 mW

Option b) 100 nm, 0.0059 mW is the correct answer

Explanation:

Given that the instrument here is an interferometer.

Maximum intensity is obtained when the two waves are exactly in phase.

that is the peaks (crusts and troughs) and nodes (zero value points) of the two waves will be at the exact same point when the wave falls on the detector.

The phase factor of this point is taken as ∅ = 0

Now, to get a minimum point, the phase difference between the two waves should be should be ∅ = π

This corresponds to a path difference between the two waves as half of the wavelength. λ/2

The light gets reflected from the mirror.

Hence, when we move the mirror by a length l, the extra/less path the light has to travel is 2l (light is going and coming back)

hence, to get a path difference of λ/2 the mirror should move half of this distance only

so, the mirror should move;

$l$ = λ/4