JEE Mains · Physics · STD 12 - 3. current electricity
Five identical cells each of internal resistance \(1\, \Omega\) and \(emf \;5\, {V}\) are connected in series and in parallel with an external resistance \('R'.\) For what value of \('R',\) current in series and parallel combination will remain the same ? (in \(\Omega\))
- A \(1\)
- B \(25\)
- C \(5\)
- D \(10\)
Answer & Solution
Correct Answer
(A) \(1\)
Step-by-step Solution
Detailed explanation
\(i_{1}=\frac{25}{5+R}\) \(i_{2}=\frac{5}{R+\frac{1}{5}}\) \(i_{1}=i_{2} \Rightarrow 5\left(R+\frac{1}{5}\right)=5+R\) \(4 R=4\) \(R=1\, \Omega\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- A \(10\,m\) long horizontal wire extends from North East to South West. It is falling with a speed of \(5.0\,ms^{-1},\) at right angles to the horizontal component of the earth’s magnetic field, of \(0.3\times 10^{-4}\,Wb/m^2\). The value of the induced \(emf\) in wire isJEE Mains 2019 Medium
- A sonometer wire oflength \(1.5\ m\) is made of steel. The tension in it produces an elastic strain of \(1 \%\). What is the fundamental frequency of steel if density and elasticity of steel are \(7.7 \times 10^3 \) \(kg/m^3\) and \(2.2 \times 10^{11}\) \(N/m^2\) respectively?JEE Mains 2013 Easy
- In a carnot engine, the temperature of reservoir is \(527^{\circ} C\) and that of \(\operatorname{sink}\) is \(200 \; K\). If the workdone by the engine when it transfers heat from reservoir to sink is \(12000 \; kJ\), the quantity of heat absorbed by the engine from reservoir is \(\times 10^{6} \; J\)JEE Mains 2022 Medium
- A parallel plate capacitor with air between the plate has a capacitance of \(15 pF\). The separation between the plate becomes twice and the space between them is filled with a medium of dielectric constant \(3.5.\) Then the capacitance becomes \(\frac{ x }{4}\,pF\).The value of \(x\) is \(............\)JEE Mains 2023 Medium
- If \(n\) represents the actual number of deflections in a converted galvanometer of resistance \(G\) and shunt resistance \(S\). Then the total current I when its figure of merit is \(K\) will beJEE Mains 2022 Medium
- From the top of a tower, a ball is thrown vertically upward which reaches the ground in \(6 \,s\). A second ball thrown vertically downward from the same position with the same speed reaches the ground in \(1.5\, s\). A third ball released, from the rest from the same location, will reach the ground in........ \(s\).JEE Mains 2022 Hard
More PYQs from JEE Mains
- If the set of all \(\mathrm{a} \in \mathrm{R}-\{1\}\), for which the roots of the equation \((1-a) x^2+2(a-3) x+9=0\) are positive is \((-\infty,-\alpha] \cup[\beta, \gamma)\), then \(2 \alpha+\beta+\gamma\) is equal to _______ .JEE Mains 2025 Medium
- Given below are two statements: One is labelled as Assertion \(A\) and the other is labelled as Reason \(R\). Assertion \(A:\) For measuring the potential difference across a resistance of \(600\,\Omega\), the voltmeter with resistance \(1000\,\Omega\) will be preferred over voltmeter with resistance \(4000\,\Omega\). Reason \(R:\) Voltmeter with higher resistance will draw smaller current than voltmeter with lower resistance. In the light of the above statements, choose the most appropriate answer from the options given below.JEE Mains 2023 Medium
- The rain drop of mass \(1\) g, starts with zero velocity from a height of \(1\) km. It hits the ground with a speed of \(5\) m/s. The work done by the unknown resistive force is _______ J. (take \(g = 10\) m/s\(^2\))JEE Mains 2026 Medium
- Let \(f :(0,1) \rightarrow R\) be a function defined by \(f(x)=\frac{1}{1-e^{-x}}\), and \(g(x)=(f(-x)-f(x))\). Consider two statement: \((I)\) \(g\) is an increasing function in \((0,1)\) \((II)\) \(g\) is one-one in \((0,1)\) Then,JEE Mains 2023 Hard
- The positive integer n, for which the solutions of the equation \( x(x+2)+(x+2)(x+4)+....+(x+2n-2)(x+2n) = \frac{8n}{3} \) are two consecutive even integers, is :-JEE Mains 2026 Hard
- Match List-I with List-II.
Choose the correct answer from the options given below :List-I (Relation) List-II (Law) A. \(\oint \overrightarrow{ E } \cdot \overrightarrow{ d } l =-\frac{ d }{ dt } \oint \overrightarrow{ B } \cdot \overrightarrow{ d a}\) I. Ampere's circuital law. B. \(\oint\) B. \(\vec{d} l=\mu_0\left(1+\epsilon_0 \frac{d \phi_E}{d t}\right)\) II. Faraday's laws of electromagnetic induction. C. \(\oint \overrightarrow{ E } . \overrightarrow{ d a}=\frac{1}{\epsilon_0} \int \rho dv\) III. Ampere-Maxwell law D. \(\oint \overrightarrow{ B } \cdot \overrightarrow{ d } l =\mu_0 I\) IV. Gauss's law of electrostatics JEE Mains 2026 Easy