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Physics · 2026 · 2 marks
CBSE 2026 · Region 3 · Set 1 · Q17
(a) In the given figure, a steady current I flows through the circuit when points A and C are connected by a wire of negligible resistance. Find the…
In the given figure, a steady current I flows through the circuit when points A and C are connected by a wire of negligible resistance. Find the potential difference between points B and C .
A battery of emf $\displaystyle 21$ V and internal resistance $\displaystyle 3 \Omega$ is connected to a resistor. If the current in the circuit is $\displaystyle 3$ A , find :
(i)
the resistance of the resistor.
(ii)
the terminal voltage of the battery.
Marking-scheme solution
(a)
$\displaystyle \mathrm{I}=\dfrac{\varepsilon_{n e t}}{R_{n e t}}=\dfrac{2}{4}=0.5 \mathrm{~A}$
$\displaystyle V_{BC}=-\varepsilon_{2}-I r_{2}=-4-(0.5 \times 3)=-5.5 \mathrm{~V}$
OR
(b)(i)
$\displaystyle \mathrm{IR}=\varepsilon-I r$
$\displaystyle \mathrm{R}=\dfrac{21-(3 \times 3)}{3}=4\ \Omega$
(ii)
$\displaystyle \mathrm{V}=\mathrm{IR}=3 \times 4=12 \mathrm{~V}$
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