Question

Which the following series fall in the visible range of electromagnetic spectrum?

• A. Brackett series
• B. Lyman series
• C. Balmer series
• D. Paschan series

Answer 1

Answer: (C)

Balmer series

Answer 2

$\frac { 1 } { \lambda }$= R $\left[ \frac { 1 } { \mathrm { n } _ { \mathrm { f } } ^ { 2 } } - \frac { 1 } { \mathrm { n } _ { \mathrm { i } } ^ { 2 } } \right]$

Balmer Series; n_f = 2; n_i = 3, 4, 5.....

$\left[ \frac { 1 } { 4 } - \frac { 1 } { 9 } \right]$

$\left[ \frac { 5 } { 36 } \right]$

λ = $\frac { 36 } { 5 }$ × $\frac { 10 ^ { - 7 } } { 1.097 }$ m

λ = 6.56 × 10^–7 m

$\lambda = 656 \times 10 ^ { - 9 } \mathrm {~m}$

This wavelength falls in visible range.