Question

A photon of wavelength 6630 Å is incident on a totally reflecting surface. The momentum delivered by the photon is equal to-

• A. 6.63 × 10^–27 kg-m/sec
• B. 2 × 10^–27 kg-m/sec
• C. 10^–27 kg-m/sec
• D. None of these

Answer 1

Answer: (B)

2 × 10^–27 kg-m/sec

Answer 2

Dp = 2p = 2(h/l)

= $\frac { 2 \times 6.62 \times 10 ^ { - 34 } } { 6630 \times 10 ^ { - 10 } }$

= $\frac { 2 \times 6.62 } { 6.63 }$ × 10^{–34 + 7}

= 2 × 10^–27 kg–m/sec