A particular station of All India Radio, New Delhi, broadcasts on a frequency of 1,368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is : [speed of light, $\mathrm{c}=3.0\times {10}^{8 }{\mathrm{ms}}^{-1}$]

1. 2192 m

2. 21.92 cm

3. 219.3 m

4. 219.2 m

A monochromatic infrared range finder of power 1mW emits photons with wavelength 1000 nm in 0.1 second. The number of photons emitted in 0.1 second is-
(Given -h = \(6.626 \times 10^{-34} J~s\) , \(c = 3 \times 10^8 m~s^{-1}, \) Avogadro number = \(6.022 \times 10^{23}\))
1. \(30 \times 10^{37}\)
2. \(5 \times 10^{14} \)
3. \(30 \times 10^{34} \)
4. \(5 \times 10^{11} \)