ELECTROMAGNETIC WAVES ELECTROMAGNETIC WAVES PREVIOUS QUESTIONS ELECTROMAGNETIC WAVES

ELECTROMAGNETIC WAVES

ELECTROMAGNETIC WAVES PREVIOUS QUESTIONS

ELECTROMAGNETIC WAVES

ELECTROMAGNETIC WAVES Solution: Em wave KEY: 2

ELECTROMAGNETIC WAVES

ELECTROMAGNETIC WAVES Solution: KEY: 4

ELECTROMAGNETIC WAVES 3) A red LED emits light at 0. 1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is [J. M. O. L - 2015] 1) 1. 73 V/m Solution: 2) 2. 45 V/m 3) 5. 48 V/m 4) 0. 75 V/m

ELECTROMAGNETIC WAVES 4) Match list I (Wavelength range of electromagnetic spectrum) with list II. (Method of production of these waves) and select the correct option from the options gives the lists [J. M. L. O - 2014] List - II 1) 700 mm to 1 mm 1) Vibration of atoms and molecules 2) 1 nm to 400 nm 2) Inner shell electrons in atoms moving from one energy level to a lower level 3) Radioactivity decay of the nucleus 4) 1 mm to 0. 1 m 4) Radioactive decay of the nucleus 4) Magnetron value.

ELECTROMAGNETIC WAVES 1) (1) -(iv), (2)-(iii), (3)-(ii), (4)-(i) 2) (1) -(iii), (2)-(iv), (3)-(i), (4)-(ii) 3) (1) -(ii), (2)-(iii), (3)-(iv), (4)-(i) 4) (1) -(i), (2)-(ii), (3)-(iii), (4)-(iv) Solution:

ELECTROMAGNETIC WAVES Solution:

ELECTROMAGNETIC WAVES 6) A lamp emits monochromatic green light uniformly in all directions The lamp is 3% efficient in converting electrical power to electromagnetic waves and consumes 100 W of power. The amplitude of the electromagnetic radiation at a distance of 5 m from the lamp will be nearly [J. M. L. O - 2014] 1) 1. 34 V/m Solution: 2) 2. 68 V/m 3) 4. 02 V/m 4) 5. 36 V/m

ELECTROMAGNETIC WAVES Solution: Flux passing through area

ELECTROMAGNETIC WAVES ××× × ××××× R ××××× ×× × × 1) E 3) E 2) E R r 4) E R r

ELECTROMAGNETIC WAVES Solution: KEY: 1

ELECTROMAGNETIC WAVES 1) 0. 7 Solution: 4) 0. 6

ELECTROMAGNETIC WAVES 10) The magnetic field in a travelling electromagnetic wave has a peak value of 20 n. T. The peak value of electric field strength is…. . [JEE 2013] Solution: B = 20 n. T E=?

ELECTROMAGNETIC WAVES 11) Photons of an electromagnetic radiation has an energy 11 ke. V each. To which region of electromagnetic spectrum does it belong ? [JEE MAINS ONLINE-2013] 1) Infrared region 2) X-rays region 3) Visible region Solution: 4) Ultra violet region

ELECTROMAGNETIC WAVES 12) This question has statement-I and statement-II of the four choices given after the statements, choose the one that best describes the two statements. Statement-I: Short wave transmission is achieved due to the total internal reflection of the e-m wave from an appropriate height in the ionosphere. Statement –II: Refractive index of a plasma is independent of the frequency of e-m waves. [JEE MAINS ONLINE-2013]

ELECTROMAGNETIC WAVES 1) Statement I is true, statement II is true statement II is a correct explanation for statement I 2) Statement I is false, statement II is true 3) Statement I is true, statement II is false 4) Statement I is true, statement II is true but statement II is not the correct explanation for statement I Solution: Conceptual

ELECTROMAGNETIC WAVES 13) Select the correct statement from the following: [JEE MAINS ONLINE-2013] 1) Electromagnetic waves cannot travel in vacuum 2) electromagnetic waves are longitudinal waves 3) electromagnetic waves are produced by charge moving with uniform velocity 4) electromagnetic wave carry both energy and momentum as they prorogate through space Solution: Conceptual

ELECTROMAGNETIC WAVES Solution: From given problem

ELECTROMAGNETIC WAVES 15) This question has statement-I and statement-II of the four choices given after the statements, choose the one that best describes the two statements. Statement-I: Out of radio waves and microwaves, the radio waves undergo more diffraction. Statement –II: radio waves have greater frequency compared to microwaves. [JEE MAINS ONLINE-2013]

ELECTROMAGNETIC WAVES 1) Statement I is true, statement II is true statement II is a correct explanation for statement I 2) Statement I is false, statement II is true 3) Statement I is true, statement II is false 4) Statement I is true, statement II is true but statement II is not the correct explanation for statement I Solution: Conceptual

ELECTROMAGNETIC WAVES 1) 5. 8 2) 2. 4 3) 4. 8 4) 8. 2 Solution:

ELECTROMAGNETIC WAVES 17) The rms value of the electric field of the light coming from the sun is 720 N/C. The average total energy density of the electromagnetic wave is. . . 1) 3. 3 10 -3 J/m 3 2) 4. 58 10 -6 J/m 3 3) 6. 37 10 -9 J/m 3 4) 81. 35 10 -12 J/m 3 Solution: Total average energy = 0 E 2 rms = 8. 85 10 -12 (720)2

ELECTROMAGNETIC WAVES 18) An electromagnetic wave of frequency 3 MHz passes from Vacuum into a dielectric medium with permittivity ∈=4. 0. Then 1) Wave length doubled and frequency remains unchanged. 2) Wave length is doubled and frequency be comes half 3) Wave length is halved and frequency remains unchanged. 4) Wave length and frequency both remains unchanged. Solution: Conceptual

ELECTROMAGNETIC WAVES 19) Which one of the following electromagnetic radiation have the smallest wavelength ? [AIEEE 2003] 1) ultraviolet waves 2) X- rays 4) microwaves

ELECTROMAGNETIC WAVES Solution: We know that

ELECTROMAGNETIC WAVES 21) Which of the following rays are not electromagnetic wave? [AIEEE 2002] 1) X-rays 4) Heat rays

ELECTROMAGNETIC WAVES 22) Arrange the following electromagnetic radiation per quantum in the order of increasing energy: [AIEEE 2016] A: Blue light B: Yellow light C: X-ray D: Radio wave 1) D, B, A, C 2) A, B, D, C 3) C, A, B, D 4) B, A D, C Solution: Conceptual

ELECTROMAGNETIC WAVES 23) Consider an electromagnetic wave propagating in vacuum. Choose the correct statement: [AIEEE 2016]

ELECTROMAGNETIC WAVES Solution: KEY: 4

ELECTROMAGNETIC WAVES Thank you…