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Day 491: JEE Mains Physics

5 questions. Try each one first, then open its answer.

  1. Question 1

    Atoms. Asked once: 6 Apr 2023

    119
    Experimentally it is found that 12.8eV12.8eV energy is required to separate a hydrogen atom into a proton and an electron. So the orbital radius of the electron in a hydrogen atom is 9x×10−10 m\frac{9}{x}\times10^{- 10}\text{ }m. The value of the xx is____ (1eV=1.6×10−19 J,14πϵ0=9×109Nm2/C2\left( 1eV = 1.6 \times10^{- 19}\text{ }J,\frac{1}{4\pi\epsilon_{0}}= 9 \times10^{9}Nm^{2}/C^{2} \right. and electronic charge =1.6×10−19 C= 1.6 \times10^{- 19}\text{ }C )

  2. Question 2

    Current Electricity. Asked once: 23 Jan 2026 S1

    9
    A wire of uniform resistance λΩ/m\lambda\Omega/m is bent into a circle of radius rr and another piece of wire with length 2r2r is connected between points A and B (AOB)(AOB) as shown in figure. The equivalent resistance between points A and B is ____\_\_\_\_ Ω\Omega.

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  3. Question 3

    Dual Nature of Radiation and Matter. Asked once: 31 Jan 2024

    101
    In a photoelectric effect experiment a light of frequency 1.5 times the threshold frequency is made to fall on the surface of photosensitive material. Now if the frequency is halved and intensity is doubled, the number of photo electrons emitted will be:

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  4. Question 4

    Electromagnetic Induction. Asked once: 23 Jan 2025

    1
    Regarding self-inductance : (A) The self-inductance of the coil depends on its geometry. (B) Self-inductance does not depend on the permeability of the medium. (C) Self-induced e.m.f. opposes any change in the current in a circuit. (D) Self-inductance is electromagnetic analogue of mass in mechanics. (E) Work needs to be done against self-induced e.m.f. in establishing the current.Choose the correct answer from the options given below:

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  5. Question 5

    Electromagnetic Waves. Asked once: 28 Jun 2022

    11
    A radar sends an electromagnetic signal of electric field (E0)=2.25 V/m\left( E_{0} \right)= 2.25\text{ }V/m and magnetic field (B0)=1.5×10−8 T\left( B_{0} \right)= 1.5 \times10^{- 8}\text{ }T which strikes a target on line of sight at a distance of 3 km3\text{ }km in a medium. After that, a part of the signal (echo) reflects back towards the radar with the same velocity and by same path. If the signal was transmitted at time t0t_{0} from the radar, then after how much time echo will reach to the radar?

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