JEE Mains · Physics · STD 12 - Current electricity
- JEE Mains 2022
- Hard
- Numerical
In the given circuit ' \(a\) ' is an arbitrary constant. The value of \(m\) for which the equivalent circuit resistance is minimum, will be \(\sqrt{\frac{ x }{2}}\). The value of \(x\) is ...........

Pick an option to check your answer.
Answer & Solution
Correct Answer
(A) \(3\)
Step-by-step Solution
Detailed explanation
\(R =\left(\frac{ ma }{3}\right)+\left(\frac{ a }{2 m }\right)\)
\(\frac{ dR }{ dm }=\frac{ a }{3}-\frac{ a }{2 m ^{2}}=0\)
\(\frac{ a }{3}=\frac{ a }{2 m ^{2}}\)
\(m ^{2}=\frac{3}{2}\)
\(m =\sqrt{\frac{3}{2}}\)
\(x =3\)
More questions from Physics
- A beam of light has two wavelengths of \(4972\,\mathop A\limits^o \) and \(6216\,\mathop A\limits^o \) with a total intensity of \(3 .6 \times 10^{- 3}\,\,Wm^{-2}\) equally distributed among the two wavelengths. The beam falls normally on an area of \(1\,cm^2\) of a clean metallic surface of work function \( 2.3\,eV.\) Assume that there is no loss of light by reflection and that each capable photon ejects one electron. The number of photoelectrons liberated in \(2\,s\) is approximatelyJEE Mains 2014 Hard
-

In the given circuit the sliding contact is pulled outwards such that electric current in the circuit changes at the rate of \(8 \mathrm{~A} / \mathrm{s}\). At an instant when R is \(12 \Omega\), the value of the current in the circuit will be ______ A.JEE Mains 2025 Medium - When radiation of wavelength \(\lambda \) is incident on a metallic surface, the stopping potential is \(4.8\) volts. If the same surface is illuminated with radiation of double the wavelength, then the stopping potential becomes \(1.6\) volts. Then the threshold wavelength for the surface isJEE Mains 2021 Hard
- A massless spring gets elongated by amount \(x_1\) under a tension of 5 N . Its elongation is \(x_2\) under the tension of 7 N . For the elongation of \(\left(5 x_1-2 x_2\right)\), the tension in the spring will be,JEE Mains 2025 Easy
- In the figure shown, after the switch \(‘S’\) is turned from position \(‘A’\) to position \(‘B’\), the energy dissipated in the circuit in terms of capacitance \(‘C’\) and total charge \(‘Q’\) is
JEE Mains 2019 Hard - Given below are two statements:
Statement I: For a mechanical system of many particles total kinetic energy is the sum of kinetic energies of all the particles.
Statement II: The total kinetic energy can be the sum of kinetic energy of the center of mass w.r.t. to the origin and the kinetic energy of all the particles w.r.t. the center of mass as the reference.
In the light of the above statements,choose the correct answer from the options given below:JEE Mains 2026 Hard
More PYQs from JEE Mains
- A solid sphere of mass \(500\,g\) and radius \(5\,cm\) is rotated about one of its diameter with angular speed of \(10\,rad \, s ^{-1}\). If the moment of inertia of the sphere about its tangent is \(x \times 10^{-2}\) times its angular momentum about the diameter. Then the value of \(x\) will be ..............JEE Mains 2023 Medium
- Two cylindrical vessels of equal cross sectional area of \(2 \mathrm{~m}^2\) contain water up to height 10 m and 6 m , respectively. If the vessels are connected at their bottom then the work done by the force of gravity is : (Density of water is \(10^3 \mathrm{~kg} / \mathrm{m}^3\) and \(\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2\))JEE Mains 2025 Medium
- In a Young's double slit experiment, light of \(500\, nm\) is used to produce an interference pattern. When the distance between the slits is \(0.05\, mm\), the angular width (in degree) of the fringes formed on the distance screen is close to\(........^o\)JEE Mains 2020 Medium
- A thin infinite sheet charge and an infinite line charge of respective charge densities \(+\sigma\) and \(+\lambda\) are placed parallel at \(5\,m\) distance from each other. Points \(P\) and \(Q\), are at \(\frac{3}{\pi} m\) and \(\frac{4}{\pi} m\) perpendicular distance from line charge towards sheet charge, respectively. \(E_P\) and \(E_Q\) are the magnitudes of resultant electric field intensities at point \(P\) and \(Q\), respectively. If \(\frac{E_p}{E_Q}=\frac{4}{a}\) for \(2|\sigma|=|\lambda|\). Then the value of \(a\) is ...........JEE Mains 2023 Hard
- The mass defect in a particular reaction is \(0.4 \mathrm{~g}\). The amount of energy liberated is \(\mathrm{n} \times 10^7 \mathrm{kWh}\), where\(\mathrm{n}=\)________. (speed of light \(=3 \times 10^8 \mathrm{~m} / \mathrm{s}\) )JEE Mains 2024 Hard