Electromagnetic Spectrum - UNSOLVED PRACTICE SET

Q7. What is the electromagnetic spectrum? List the main regions in order of increasing frequency.

Q8. Why do all electromagnetic waves travel with the same speed in vacuum, regardless of their frequency or wavelength?

Q9. How is the electromagnetic spectrum organized? What physical quantity remains constant for all EM waves in vacuum?

Q10. Compare the wavelength, frequency, and energy of radio waves and gamma rays.

Q11. What is the source of electromagnetic waves? Why can't a charge moving with constant velocity produce electromagnetic waves?

Q12. Draw a simplified diagram of the electromagnetic spectrum, labeling the approximate wavelength/frequency ranges of each region.

Q13. Describe the electromagnetic spectrum in detail. Arrange the different types of electromagnetic waves in order of increasing wavelength and discuss how the properties change across the spectrum.

Q14. Explain why the speed of all electromagnetic waves in vacuum is the same (c = 3 × 10⁸ m/s), even though their wavelengths and frequencies differ vastly. Use Maxwell's equations to support your answer.

Q15. Discuss how electromagnetic waves are produced. Why do accelerated charges emit electromagnetic radiation? Explain why a charge in uniform circular motion emits electromagnetic waves.

Q16. An electromagnetic wave has a wavelength of 600 nm in vacuum.

(a) Calculate its frequency.

(b) Calculate its wavelength when it enters glass with refractive index 1.5.

(c) Determine its speed in glass.

(d) Calculate the energy of one photon of this radiation.

Q17. A radio station broadcasts at a frequency of 98.3 MHz.

(a) Calculate the wavelength of the radio waves.

(b) Calculate the period of oscillation.

(c) Compare the energy of one photon of this radio wave with one photon of visible light (λ = 500 nm). Which has more energy and by what factor?

Q18. In your school's physics lab, students are learning about the electromagnetic spectrum using a chart that shows different types of EM waves.

(a) A student points to a region with wavelength 10⁻¹² m and says "These are X-rays used in airport security." Another student says they are gamma rays from radioactive decay. Who is correct? Explain your reasoning.

(b) Your mobile phone operates at 1800 MHz. Calculate its wavelength and identify which region of the EM spectrum it belongs to.

(c) The Sun emits maximum radiation at a wavelength of about 500 nm. Calculate the corresponding frequency and identify the region. Why does this make sense for life on Earth?

(d) A classmate asks: "If all EM waves travel at the same speed, why does light from a torch reach us instantly while radio signals from Mars take minutes?" Explain the correct physics behind this observation.