PYQ Vault
EbooksTutor

Field amplitude or intensity at a distance from a bulb of given power and efficiency

This type of question, asked 4 times: 2021 Paper 25, 14 Jun 2022, 29 Jul 2022, 30 Jan 2023. All 4 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    2021 Paper 25

    22
    A radiation is emitted by 1000 W1000\text{ }W bulb and it generates an electric field and magnetic field at PP, placed at a distance of 2 m2\text{ }m. The efficiency of the bulb is 1.25%1.25\%. The value of peak electric field at PP is x×10−1 V/mx\times10^{- 1}\text{ }V/m. Value of xx is ____\_\_\_\_. (Rounded-off to the nearest integer) [Take ε0=8.85×10−12C2 N−1 m−2,c=3×108 ms−1\varepsilon_{0}= 8.85 \times10^{- 12}C^{2}{\text{ }N}^{- 1}{\text{ }m}^{- 2},c = 3 \times10^{8}{\text{ }ms}^{- 1} ]

  2. Question 2

    14 Jun 2022

    107
    An electric bulb is rated as 200 W200\text{ }W. What will be the peak magnetic field at 4 m4\text{ }m distance produced by the radiations coming from this bulb? Consider this bulb as a point source with 3.5%3.5\% efficiency.

    Tap an option to check your answer.

  3. Question 3

    29 Jul 2022

    112
    Nearly 10%10\% of the power of a 110 W110\text{ }W light bulb is converted to visible radiation. The change in average intensities of visible radiation, at a distance of 1 m1\text{ }m from the bulb to a distance of 5 m5\text{ }m is a×10−2 W/m2a\times10^{- 2}\text{ }W/m^{2}. The value of ' aa ' will be

  4. Question 4

    30 Jan 2023

    98
    A point source of 100 W100\text{ }W emits light with 5%5\% efficiency. At a distance of 5 m5\text{ }m from the source, the intensity produced by the electric field component is:

    Tap an option to check your answer.