Download App

Current Electricity — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity3 Marks
Question
Two primary cells of emfs wire $\varepsilon_1$ and $\varepsilon_2(\varepsilon_1>\varepsilon_2)$ are connected to a potentiometer wire AB as shown in fig. If the balancing lengths for the two combinations of the cells are 250cm and 400cm, find the ratio of $\varepsilon_1$ and $\varepsilon_2.$
✓

Answer

In first combination $\varepsilon_1$ and $\varepsilon_2$ are opposing each other while in second combination $\varepsilon_1$ and $\varepsilon_2$ are adding each other,
So,
$\varepsilon_1-\varepsilon_2=\text{Kl}_1$
$\varepsilon_1+\varepsilon_2=\text{kl}_2$
$\frac{\varepsilon_1-\varepsilon_2}{\varepsilon_1+\varepsilon_2}=\frac{\text{l}_1}{\text{l}_1}$
$\Rightarrow\frac{\varepsilon_1-\varepsilon_2}{\varepsilon_1+\varepsilon_2}=\frac{250}{400}$
$\Rightarrow\frac{\varepsilon_1-\varepsilon_2}{\varepsilon_1+\varepsilon_2}=\frac{5}{8}$
$\Rightarrow8\varepsilon_1-8\varepsilon_2=5\varepsilon_1+5\varepsilon_2$
$\Rightarrow3\varepsilon_1=13\varepsilon_2$
$\therefore\frac{\varepsilon_1}{\varepsilon_2}=\frac{13}{3}$
$\therefore\varepsilon_1:\varepsilon_2=13:32$

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 "3 Marks Question" from Current Electricity→Current Electricity — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

Two waves, travelling in the same direction through the same region, have equal frequencies, wavelengths and amplitudes. If the amplitude of each wave is 4mm and the phase difference between the waves is 90°, what is the resultant amplitude?
→
Calculate the magnetic dipole moment corresponding to the motion of the electron in the ground state of a hydrogen atom.
→
Compute the typical de Broglie wavelength of an electron in a metal at $27^\circ C$ and compare it with the mean separation between two electrons in a metal which is given to be about $2 \times 10^{–10} m.$
→
A small piece of wood is floating on the surface of a 2.5m deep lake. Where does the shadow form on the bottom when the sun is just setting? Refractive index of water $=\frac{4}{3}.$
→
Explain the principle and working of a cyclotron with the help of a schematic diagram. Write the expression for cyclotron frequency.
→
$a.$ Using the Bohr's model, calculate the speed of the electron in a hydrogen atom in the $n = 1, 2$ and $3$ levels.
$b$. Calculate the orbital period in each of these levels.
→
Identify the logic gate represented by the following circuit by writing its truth table:
→
A capacitor of capacitance $10\mu\text{F}$ is connected across a battery of emf 6.0V through a resistance of $20\text{k}\Omega$ for 4.0s. The battery is then replaced by a thick wire. What will be the charge on the capacitor 4.0s after the battery is disconnected?
→
Why are alloys used for making standard resistance coils?
→
If three helium nuclei combine to form a carbon nucleus, energy is liberated. Why can't helium nuclei combine on their own and minimise the energy?
→