# Electromagnetic Waves-CBSE Class 12th NCERT Solution

Get, detailed solutions to the questions of the chapter Electromagnetic Waves from NCERT textbooks

Get, detailed solutions to the questions of the chapter **Electromagnetic Waves** from NCERT textbooks. The objective is to helping students regarding the pattern of answering the question as per the cbse latest marking scheme.**Cbse.jagranjosh.com** provided you NCERT solutions for classes 12th math and science subjects.

**Some questions of this chapter are given here**

**Q.** Figure 8.6 shows a capacitor made of two circular plates each of radius 12 cm, and separated by 5.0 cm. The capacitor is being charged by an external source (not shown in the figure). The charging current is constant and equal to 0.15.

a) Calculate the capacitance and the rate of charge of potential difference between the plates.

b) Obtain the displacement current across the plates.

c) Is Kirchhoff’s first rule (junction rule) valid at each plate of the capacitor? Explain.

**Q. **A parallel plate capacitor (Fig. 8.7) made of circular plates each of radius R = 6.0 cm has a capacitance C = 100 pF. The capacitor is connected to a 230 V ac supply with a (angular) frequency of 300 rads–1.

a) What is the rms value of the conduction current?

b) Is the conduction current equal to the displacement current?

c) Determine the amplitude of B at a point 3.0 cm from the axis between the plates.

**Q.** What physical quantity is the same for X-rays of wavelength 10–10 m, red light of wavelength 6800 Å and radio waves of wavelength 500m?

**Q. **The terminology of different parts of the electromagnetic spectrum is given in the text. Use the formula E = hν (for energy of a quantum of radiation: photon) and obtain the photon energy in units of eV for different parts of the electromagnetic spectrum. In what way are the different scales of photon energies that you obtain related to the sources of electromagnetic radiation?

**Q. **In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of 2.0 × 1010 Hz and amplitude 48 V m–1.

a) What is the wavelength of the wave?

b) What is the amplitude of the oscillating magnetic field?

c) Show that the average energy density of the E field equals the average energy density of the B field. [c = 3 × 108 m s–1.]

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