Physics Test 215

The Huygens–Fresnel principle (named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel) is a method of analysis applied to problems of wave propagation both in the far-field limit and in near-field diffraction.

It states that every point on a wavefront is itself the source of spherical wavelets. The sum of these spherical wavelets forms the wavefront.

An apparent change in the frequency of waves, as of sound or light, occurring when the source and observer are in motion relative to each other, with the frequency increasing when the source and observer approach each other anddecreasing when they move apart.

A perpendicular drawn to the surface of a wavefront at any point in the direction of propagation of light is called as wave normal. The direction of propagation of a wave front is given by a ray of light. Therefore, a wave normal represents a ray of light.

Here, path difference Δx=0.8m Frequency n =120 Hz Phase difference is ϕ=0.5π The phase difference is given by

 Hence, the wave velocity is given by v = nλ (where λ is the wavelength of wave) =120 × 2.3 = 384m/s

The wave number of the photon emitted because of the electron transition is

ν' = 1/λ = R(1/(n₁)² – 1/(n₂)²) where λ is the wave length of the photon and R is Rydberg’s constant.

The momentum of the photon is p = h/λ = hR(1/(n₁)² – 1/(n₂)²) where h is Planck’s constant.

When the photon is emitted with this momentum, the atom recoils (like a gun firing a bullet) with an equal and opposite momentum. Therefore, the recoil velocity of the atom is given by

v = p/M = (hR/M)(1/(n₁)² – 1/(n₂)²).

 In parallel combination  E_eq=E=6V

F= qE

a = qE/m -------(1)

start from rest so u= 0

v= u+ at

v= at

from 1

v= qEt/m

kinetic energy= 1/2 mv²

KE= q²E²t²/2m