Electric Resistance and Simple Circuits | Physics JEE previous year questions with Solutions

Q 21 :

In the given circuit, the current $(I)$ through the battery will be [2023]

1.5 A
1 A
2.5 A
2 A

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(1)

$In the circuit D_{1} and D_{3} are forward biased and D_{2} is reverse biased.$

$∴$ $I = \frac{10}{20 / 3} = \frac{10 \times 3}{20} = \frac{3}{2} A = 1.5 A$

Q 22 :

In the given circuit, the equivalent resistance between the terminal A and B is ________ $Ω$ . [2023]

0%

(10)

$R_{A B} = 3 + 1 + 6 = 10 Ω$

Q 23 :

If the potential difference between $B$ and $D$ is zero, the value of $x$ is $\frac{1}{n} Ω$ . The value of $n$ is ______. [2023]

0%

(2)

$\frac{2}{3} = \frac{\frac{x}{x + 1}}{x}$

$\Rightarrow \frac{2}{3} = \frac{1}{x + 1}$

$\Rightarrow x = 0.5 = \frac{1}{2}$

$\Rightarrow n = 2$

Q 24 :

10 resistors each of resistance 10 $Ω$ can be connected in such a way as to get maximum and minimum equivalent resistance. The ratio of maximum and minimum equivalent resistance will be ________. [2023]

0%

(100)

Maximum resistance occurs

When all the resistors are connected in series combination

$∴$ $R_{\max} = 10 R$

$Here R = 10 Ω$

Minimum resistance occurs

When all the resistances are connected in parallel combination

$R_{\min} = \frac{R}{10}$

$∴$ $\frac{R_{\max}}{R_{\min}} = 100$

Q 25 :

A wire of uniform resistance $λ Ω / m$ is bent into a circle of radius $r$ and another piece of wire with length $2 r$ is connected between points A and B (AOB) as shown in the figure. The equivalent resistance between points A and B is _______ $Ω$ . [2026]

$2 π λ r$
$\frac{3 π λ r}{8}$
$\frac{6 π λ r}{3 π + 16}$
$(π + 1) 2 r λ$

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(3)

Q 26 :

A regular hexagon is formed by six wires each of resistance $r Ω$ and the corners are joined to the centre by wires of same resistance. If the current enters at one corner and leaves at the opposite corner, the equivalent resistance of the hexagon between the two opposite corners will be [2026]

$\frac{3}{4} r$
$\frac{4}{5} r$
$\frac{5}{8} r$
$\frac{3}{5} r$

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(2)

Q 27 :

Two known resistances of $R Ω a n d 2 R Ω$ and one unknown resistance $X Ω$ are connected in a circuit as shown in the figure. If the equivalent resistance between points A and B in the circuit is $X Ω$ then the value of X is ______ $Ω .$ [2026]

$(\sqrt{3} - 1) R$
$2 (\sqrt{3} - 1) R$
R
$(\sqrt{3} + 1) R$

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