Question:
Two sources of equal emfs are connected in series. This combination is connected to an external resistance R. The internal resistances of the two sources are r1 and r2 (r1 > r2). If the potential difference across the source of internal resistance r1 is zero, then the value of R will be :
Two sources of equal emfs are connected in series. This combination is connected to an external resistance R. The internal resistances of the two sources are r1 and r2 (r1 > r2). If the potential difference across the source of internal resistance r1 is zero, then the value of R will be :
Updated On: Mar 19, 2025
\(r_1-r_2\)
\(\frac{r_1r_2}{r_1+r_2}\)
\(\frac{r_1+r_2}{2}\)
\(r_2-r_1\)
Hide Solution
Verified By Collegedunia
The Correct Option is A
Solution and Explanation
The correct answer is (A) : \(r_1-r_2\)
\(ΔV=0 ⇒\frac{2ε}{r_1+r_2+R}r_1=ε\)
\(⇒R=r_1-r_2\)
Was this answer helpful?
0
0
Top Questions on Electromagnetic induction
- If $ \epsilon_0 $ denotes the permittivity of free space and $ \Phi_E $ is the flux of the electric field through the area bounded by the closed surface, then the dimension of $ \epsilon_0 \frac{d\Phi_E}{dt} $ are that of:
- JEE Main - 2025
- Physics
- Electromagnetic induction
- A coil has 100 turns, each of area \( 0.05 \, \text{m}^2 \) and total resistance \( 1.5 \, \Omega \). It is inserted at an instant in a magnetic field of \( 90 \, \text{mT} \), with its axis parallel to the field. The charge induced in the coil at that instant is:
- CBSE CLASS XII - 2025
- Physics
- Electromagnetic induction
- Which of the following devices is based on the principle of electromagnetic induction?
- Bihar Board XII - 2025
- Physics
- Electromagnetic induction
- State Lenz’s law. A rod MN of length \( L \) is rotated about an axis passing through its end M perpendicular to its length, with a constant angular velocity \( \omega \) in a uniform magnetic field \( \vec{B} \) parallel to the axis. Obtain an expression for emf induced between its ends.
- CBSE CLASS XII - 2025
- Physics
- Electromagnetic induction
- Which of the following statements is not correct for electromagnetic induction?
- CUET (UG) - 2025
- Physics
- Electromagnetic induction
View More Questions
Questions Asked in JEE Main exam
Let $ f: \mathbb{R} \to \mathbb{R} $ be a twice differentiable function such that $$ f''(x)\sin\left(\frac{x}{2}\right) + f'(2x - 2y) = (\cos x)\sin(y + 2x) + f(2x - 2y) $$ for all $ x, y \in \mathbb{R} $. If $ f(0) = 1 $, then the value of $ 24f^{(4)}\left(\frac{5\pi}{3}\right) $ is:
- JEE Main - 2025
- Differential Calculus
- A 400 g solid cube having an edge of length \(10\) cm floats in water. How much volume of the cube is outside the water? (Given: density of water = \(1000 { kg/m}^3\))
- An infinite wire has a circular bend of radius \( a \), and carrying a current \( I \) as shown in the figure. The magnitude of the magnetic field at the origin \( O \) of the arc is given by:
- JEE Main - 2025
- Magnetic Field
- Let \( A = [a_{ij}] \) be a matrix of order 3 \(\times\) 3, with \(a_{ij} = (\sqrt{2})^{i+j}\). If the sum of all the elements in the third row of \( A^2 \) is \( \alpha + \beta\sqrt{2} \), where \(\alpha, \beta \in \mathbb{Z}\), then \(\alpha + \beta\) is equal to:
- JEE Main - 2025
- Matrices and Determinants
- Total number of non-bonded electrons present in \( \text{NO}_2 \); ion based on Lewis theory is:
- JEE Main - 2025
- Chemical bonding and molecular structure
View More Questions
Concepts Used:
Electromagnetic Induction
Electromagnetic Induction is a current produced by the voltage production due to a changing magnetic field. This happens in one of the two conditions:-
- When we place the conductor in a changing magnetic field.
- When the conductor constantly moves in a stationary field.
Formula:
The electromagnetic induction is mathematically represented as:-
e=N × d∅.dt
Where
- e = induced voltage
- N = number of turns in the coil
- Φ = Magnetic flux (This is the amount of magnetic field present on the surface)
- t = time
Applications of Electromagnetic Induction
- Electromagnetic induction in AC generator
- Electrical Transformers
- Magnetic Flow Meter