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Intensity, Power and Amplitude for JEE: 21 solved questions

Real JEE paper questions on intensity, power and amplitude, part of electromagnetic waves. Each opens with the options, the correct answer and a step-by-step solution. Papers run from 2015 to 2026. No sign-in needed to read them.

What this topic asks

• Intensity from the amplitudes — 12 questions
• Inverse-square scaling and intensity in a medium — 5 questions
• Point source, efficiency and power on an area — 4 questions

All 21 questions with solutions

• The equation of the electric field of an electromagnetic wave propagating through free space is given by, E =… JEE Main 23rd Jan 1st Shift 2026
• In the given electromagnetic wave E_y = 600 sin(ω t - kx) Vm⁻¹, intensity of the associated light beam is (in… JEE Main 6th April 2nd Shift 2024
• A plane electromagnetic wave propagating in x-direction is described by E_y = (200 Vm⁻¹) sin[1.5 × 10⁷ t - 0.… JEE Main 27th Jan 1st Shift 2024
• The electric field in an electromagnetic wave is given by E = 56.5 sin(ω(t - x/c)) N C⁻¹. Find the intensity… JEE Main 25th June 1st Shift 2022
• A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a… JEE Main 2015
• A radiation is emitted by 1000 W bulb and it generates an electric field and magnetic field at P, placed at a… JEE Main 26th Feb 1st Shift 2021
• A point source of 100 W emits light with 5% efficiency. At a distance of 5 m from the source, the intensity p… JEE Main 30th Jan 2nd Shift 2023
• An electric bulb is rated as 200 W. What will be the peak magnetic field at 4 m distance produced by the radi… JEE Main 24th June 2nd Shift 2022
• A 27 mW laser beam has a cross-sectional area of 10 mm². The magnitude of the maximum electric field in this… JEE Main 11th Jan 2nd Shift 2019
• The mean intensity of radiation on the surface of the Sun is about 10⁸ W/m². The rms value of the correspondi… JEE Main 12th Jan 2nd Shift 2019
• A plane electromagnetic wave of wavelength λ has an intensity I. It is propagating along the positive Y-direc… JEE Main Online 2018
• The intensity of the light from a bulb incident on a surface is 0.22 W/m². The amplitude of the magnetic fiel… JEE Main 29th June 1st Shift 2022
• Suppose that intensity of a laser is (315/π) W/m². The rms electric field, in units of V/m associated with th… JEE Main 6th Sept 1st Shift 2020
• Intensity of sunlight is observed as 0.092 Wm⁻² at a point in free space. What will be the peak value of magn… JEE Main 22nd July 2nd Shift 2021
• A laser beam has intensity of 4.0 × 10¹⁴ W/m². The amplitude of magnetic field associated with beam is T. (Ta… JEE Main 22nd Jan 2nd Shift 2026
• A plane electromagnetic wave, has frequency of 2.0 × 10¹⁰ Hz and its energy density is 1.02 × 10⁻⁸ J/m³ in va… JEE Main 2nd Sept 1st Shift 2020
• A point source is kept at the center of a spherically enclosed detector. If the volume of the detector increa… JEE Main 24th Jan 2nd Shift 2026
• Nearly 10% of the power of a 110 W light bulb is converted to visible radiation. The change in average intens… JEE Main 29th July 2nd Shift 2022
• The electric field intensity produced by the radiation coming from a 100 W bulb at a distance of 3 m is E. Th… JEE Main 17th March 2nd Shift 2021
• An electromagnetic wave of intensity 50 W m⁻² enters in a medium of refractive index 'n' without any loss. Th… JEE Main 11th Jan 1st Shift 2019
• A light wave is incident normally on a glass slab of refractive index 1.5. If 4% of light gets reflected and… JEE Main 12th Jan 1st Shift 2019