A zone plate of focal length 60 cm behaves like convex lens, if wavelength of incidence light is 6000 mathringA, then radius of first half period zone will be :

Question

A zone plate of focal length 60 cm behaves like convex lens, if wavelength of incidence light is 6000 mathringA, then radius of first half period zone will be : (A)  36× 10-8 m (B)  6× 10-8 m (C)  √6× 10-8 m (D)  6× 10-4 m

Tardigrade Admin · Accepted Answer

Radius of half period zone =√n b λ Radius of Ist zone =√1 × 60 × 10-2 × 6 × 10-7 =6 × 10-4 m

Q. A zone plate of focal length $60 c m$ behaves like convex lens, if wavelength of incidence light is $6000 \overset{˚}{A}$ , then radius of first half period zone will be :

$36 \times 1 0^{- 8} m$

$6 \times 1 0^{- 8} m$

$6 \times 1 0^{- 8} m$

$6 \times 1 0^{- 4} m$

Radius of half period zone $= nbλ$
Radius of Ist zone
$= 1 \times 60 \times 1 0^{- 2} \times 6 \times 1 0^{- 7}$
$= 6 \times 1 0^{- 4} m$

Q. A zone plate of focal length 60cm behaves like convex lens, if wavelength of incidence light is 6000A˚, then radius of first half period zone will be :

36×10−8m

6×10−8m

6​×10−8m

6×10−4m

Radius of half period zone =nbλ​ Radius of Ist zone =1×60×10−2×6×10−7​ =6×10−4m

Q. A zone plate of focal length $60 c m$ behaves like convex lens, if wavelength of incidence light is $6000 \overset{˚}{A}$ , then radius of first half period zone will be :

$36 \times 1 0^{- 8} m$

$6 \times 1 0^{- 8} m$

$6 \times 1 0^{- 8} m$

$6 \times 1 0^{- 4} m$

Radius of half period zone $= nbλ$
Radius of Ist zone
$= 1 \times 60 \times 1 0^{- 2} \times 6 \times 1 0^{- 7}$
$= 6 \times 1 0^{- 4} m$