Download App

3. current electricity — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics3. current electricity1 Mark
MCQ
A current of $2\,A$ flows through a $2\,\Omega$ resistor when connected across a battery. The same battery supplies a current of $0.5\,\, A$ when connected across a $9 \,\,\Omega$ resistor. The internal resistance of the battery is 
  • A
    $0.5 \,\Omega$
  • ✓
    $\frac{1}{3}\;\Omega $
  • C
    $\;\frac{1}{4}\;\Omega $
  • D
    $1.0\,\Omega$
✓

Answer

Correct option: B.
$\frac{1}{3}\;\Omega $
b
Let $\varepsilon $ be the emf and $r$ be internal resistance of the battery.

In the first case,

$2=\frac{\varepsilon}{2+r}$     ....$(i)$

In the second case,

$0.5=\frac{\varepsilon}{9+r}$     ....$(ii)$

Divide $(i)$ by $(ii),$ we get

${\frac{2}{0.5}=\frac{9+r}{2+r} \Rightarrow 4+2 r=4.5+0.5 r} $

${1.5 r=0.5 \Rightarrow r=\frac{0.5}{1.5}=\frac{1}{3} \,\Omega}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 3. current electricity→3. current electricity — all question types→Physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

A ray of light is incident on a $60^o$ prism at the minimum deviation position. The angle of refraction at the first face (i.e., incident face) of the prism is.......$^o$
→
A monochromatic light is travelling in a medium of refractive index $n=1.6$. It enters a stack of glass layers from the bottom side at an angle $\theta=30^{\circ}$. The interfaces of the glass layers are parallel to each other. The refractive indices of different glass layers are monotonically decreasing as $n_m=n-m / n$, where $n_m$ is the

refractive index of the $\mathrm{m}^{\text {th }}$ slab and $\Delta \mathrm{n}=0.1$ (see the figure). The ray is refracted out parallel to the interface between the $(m-1)^{\text {th }}$ and $m^{\text {th }}$ slabs from the right side of the stack. What is the value of $m$ ?

(IMAGE)

→
The work functions of Silver and Sodium are $4.6$ and $2.3 \ eV$, respectively. The ratio of the slope of the stopping potential versus frequency plot for Silver to that of Sodium is :
→
Maatch Liat $I$ List $II$

Chose the correct answer from the options given below

→
Magnets $A$ and $B$ are geometrically similar but the magnetic moment of $A$ is twice that of $B$. If $T_1 $ and $T_2$ be the time periods of the oscillation when their like poles and unlike poles are kept together respectively, then $\frac{{{T_1}}}{{{T_2}}}$will be
→
The function of rectifier is :
→
In figure a point charge $+Q_1$ is at the centre of an imaginary spherical surface and another point charge $+Q_2$ is outside it. Point $P$ is on the surface of the sphere. Let ${\Phi _s}$be the net electric flux through the sphere and ${\vec E_p}$ be the electric field at point $P$ on the sphere. Which of the following statements is $TRUE$ ?
→
The correct relation between limit of resolution and resolving power is
→
Which of the following statement is true
→
By error, a student places moving-coil voltmeter $V$ (nearly ideal) in series with the resistance in a circuit in order to read the current, as shown. The voltmeter reading will be ............ $V$
→