Irina finds an unlabeled box of fine needles, and wants to determine how thick they are. a standard ruler will not do the job, as each needle is less than a millimeter thick. so, to find the thickness, she uses a needle to poke a hole in a piece of brown construction paper. then, she positions a 640 nm laser pointer to shine through the hole and project a circular diffraction pattern on a wall 21.7 m away. she then uses her ruler to measure that the central bright circle is 14.2 cm in diameter. what diameter does irina calculate for the needle?

Explanation:

The expression which represent the first diffraction minima by a circular aperture is given by --------eqn 1

The angle through which the first minima is diffracted is given by ---------eqn 2

As is very small so we can write

So from eqn 1 and eqn 2 we can write

--------eqn 3

Here is the position of first maxima D is the distance of screen from the circular aperture d is the diameter of aperture

It is given that diameter of circular aperture is 14.7 cm so

Now putting all these value in eqn 3

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

explanation:

wheres the pic