Title 08. ELECTROMAGNETIC WAVES.pdf ✅

(1) (2) (3) (4) 7. The sun delivers of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimensions is , the radiation force on the roof will be (Assume complete absorption) (1) (2) (3) (4) 8. The average magnetic energy density of an electromagnetic wave of wave length travel‐ ling in free space is given by (1) (2) (3) (4) 9. Match the Column I and Column II Choose the correct answer from the options given below : (1) A – Q, B – R, C – P, D – S (2) A – P, B – Q, C – R, D – S (3) A – S, B – R, C – P, D – Q (4) A – S, B – P, C – R, D – Q 10. The amplitude of an electromagnetic wave in vacuum is doubled with no other changes made to the wave. As a result of this doubling of the amplitude, which of the following statement is correct? (1) The frequency of the wave changes only. (2) The wavelength of the wave changes only. (3) The speed of wave propagation changes (4) None of the above is correct. 11. Assertion : Satellite for remote sensing. Reason : Such satellite shall be in polar orbit. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 12. Light with an energy flux of falls on a non-reflecting surface at normal incidence. If the surface has an area of , the total momentum delivered (for complete absorption) during is (1) (2) (3) (4) 13. A laser beam can be focussed on an area equal to the square of its wavelength. A He-Ne laser ra‐ diates energy at the rate of and its wave‐ length is . The intensity of focussed beam will be (1) (2) (3) (4) 14. A plane electromagnetic wave of frequency 25 travels in free space along the -direction. At a perpendicular point in space and time, . What is at that point? (1) (2) (3) (4) 15. Which of the following statement(s) is/are cor‐ rect? I. Radio waves are produced by the accelerated motion of charges in conducting wires. II. Radio waves are used in radio and television communication systems. III. Cellular phones use radio waves to transmit voice communication in the ultra high frequency. (1) I and III (2) II and III (3) I and II (4) All of these 16. Find the radiation pressure of solar radiation on the surface of earth. Solar constant is (Assume complete absorption) 1.79 × 10 8 ms −1 3.08 × 10 8 ms −1 2.81 × 10 8 ms −1 1.54 × 10 8 ms −1 −−−−−−−−→ 10 3 W/m2 8 m × 20 m 1.6 × 10 5 W 7.33 × 10 −3 N 5.33 × 10 −4 N 9.33 × 10 −2 N 3.33 × 10 −5 N λ B2 2λ B2 2μ0 2B2 μ0λ B μ0λ 20 W/cm2 30 cm2 30 min 1.08 × 10 7 kg − m/s 108 × 10 4 kg − m/s 36 × 10 −4 kg − m/s 36 × 10 −5 kg − m/s 1 mW 600 nm 2.8 × 10 13 W/m2 3.2 × 10 13 W/m2 2.7 × 10 9 W/m2 3.2 × 10 9 W/m2 MHz x E = 6.3j V /m B 5.1 × 10 −8 k^T 4.1 × 10 −8 k^T 3.1 × 10 −8 ^kT 2.1 × 10 −8 ^kT 1.4 kWm−2