Question

A radio can tune to any station in the frequency range from 2.5 MHz to 15 MHz bands. What is the corresponding wavelength band?

(a) 30 m to 130 m

(b) 40 m to 140 m

(c) 20 m to 120 m

(d) 10 m to 110 m

The question was posed to me in quiz.

The doubt is from Electromagnetic Spectrum in division Electromagnetic Waves of Physics – Class 12

Answer 1

The correct answer is (c) 20 m to 120 m

Easy explanation: Maximum wavelength in the band will correspond to the lowest frequency:

c=fminλmax

λmax=\(\frac {c}{f_{min}}=\frac {3\times 10^8}{2.5\times 10^6}\)=120 m

Minimum wavelength in the band will correspond to the highest frequency:

c=fmaxλmin

λmin=\(\frac {c}{f_{max}} =\frac {3\times 10^8}{15 \times 10^6 }\)=20 m

Therefore, the corresponding wavelength band is 20 m to 120 m.