A narrow, paraxial beam of light is converging towards a point I on a screen. A plane parallel plate of glass of thickness t, and refractive index μ is introduced in the path of the beam. The convergence point is shifted by

Question

A narrow, paraxial beam of light is converging towards a point I on a screen. A plane parallel plate of glass of thickness t, and refractive index μ is introduced in the path of the beam. The convergence point is shifted by (A) t(1-1 / μ) away (B) t(1+1 / μ) away (C) t(1-1 / μ) nearer (D) t(1+1 / μ) nearer

Tardigrade Admin · Accepted Answer

Longitudinal shift is given by t-(t/μ). Hence, point of convergence shifts by the same amount.

Q. A narrow, paraxial beam of light is converging towards a point I on a screen. A plane parallel plate of glass of thickness $t$ , and refractive index $μ$ is introduced in the path of the beam. The convergence point is shifted by

$t (1 - 1/ μ)$ away

$t (1 + 1/ μ)$ away

$t (1 - 1/ μ)$ nearer

$t (1 + 1/ μ)$ nearer

Longitudinal shift is given by $t - \frac{t}{μ}$ .
Hence, point of convergence shifts by the same amount.

Q. A narrow, paraxial beam of light is converging towards a point I on a screen. A plane parallel plate of glass of thickness t, and refractive index μ is introduced in the path of the beam. The convergence point is shifted by

t(1−1/μ) away

t(1+1/μ) away

t(1−1/μ) nearer

t(1+1/μ) nearer