Current Electricity · JEE Main previous year questions

1. A.
2. B.
3. C.
4. D.

1. A.$r$
2. B.$\frac{r}{6}$
3. C.$\frac{r}{3}$
4. D.$\frac{r}{9}$

A wire of resistance R is bent into an equilateral triangle and an identical wire is bent into a square. The ratio of resistance between the two end points of an edge of the triangle to that of the square is

1. A.$8/9$
2. B.$9/8$
3. C.$32/27$
4. D.$27/32$

1. A.
2. B.
3. C.
4. D.

A wire of resistance $9\Omega$ is bent to form an equilateral triangle. Then the equivalent resistance across any two vertices will be ____ ohm.

1. A.(A), (B) and (C) only
2. B.(A), (C) and (D) only
3. C.(B), (C) and (D) only
4. D.(A), (B) and (D) only

1. A.$1.5\text{ A}$
2. B.$0.25\text{ A}$
3. C.$1.0\text{ A}$
4. D.$0.5\text{ A}$

A galvanometer having a coil of resistance $30\Omega$ need $20\text{ mA}$ of current for full-scale deflection. If a maximum current of $3\text{ A}$ is to be measured using this galvanometer, the resistance of the shunt to be added to the galvanometer should be $\frac{30}{X}\Omega$, where $X$ is

1. A.447
2. B.298
3. C.149
4. D.596

Given below are two statements : Statement-I : The equivalent emf of two nonideal batteries connected in parallel is smaller than either of the two emfs. Statement-II : The equivalent internal resistance of two nonideal batteries connected in parallel is smaller than the internal resistance of either of the two batteries. In the light of the above statements, choose the correct answer from the options given below.

1. A.Statement-I is false but Statement-II is true
2. B.Statement-I is true but Statement-II is false
3. C.Both Statement-I and Statement-II are false
4. D.Both Statement-I and Statement-II are true

1. A.
2. B.
3. C.
4. D.

1. A.$1.35\text{ A}$
2. B.$0.9\text{ A}$
3. C.$1.0\text{ A}$
4. D.$0.3\text{ A}$

A galvanometer has a coil of resistance $200\Omega$ with a full scale deflection at $20\mu \text{A}$. The value of resistance to be added to use it as an ammeter of range $(0-20)\text{mA}$ is :

1. A.$0.40\Omega$
2. B.$0.10\Omega$
3. C.$0.20\Omega$
4. D.$0.50\Omega$

1. A.$18\Omega$
2. B.$27\Omega$
3. C.$19\Omega$
4. D.$25\Omega$

1. A.$\frac{8R}{3}$
2. B.$\frac{4R}{3}$
3. C.$\frac{2}{3}R$
4. D.$\frac{5R}{3}$

1. A.1, 1
2. B.0, 1
3. C.1, 0
4. D.0, 0

At room temperature ($27^{\circ }\mathrm{C}$), the resistance of a heating element is $50\Omega$. The temperature coefficient of the material is $2.4\times 10^{-4}{}^{\circ }{\mathrm{C}}^{-1}$. The temperature of the element, when its resistance is $62\Omega$, is ____ ${}^{\circ }\mathrm{C}$.

A capacitor of reactance $4\sqrt{3}\Omega$ and a resistor of resistance $4\Omega$ are connected in series with an ac source of peak value $8\sqrt{2}\mathrm{V}$. The power dissipation in the circuit is ____ $\mathrm{W}$.

1. A.$A\cdot B$
2. B.$\bar{A}\cdot B$
3. C.$A\cdot B(A+B)$
4. D.$0$

A LCR circuit is at resonance for a capacitor C, inductance L and resistance R. Now the value of resistance is halved keeping all other parameters same. The current amplitude at resonance will be now:

1. A.halved
2. B.same
3. C.Zero
4. D.double

1. A.$3\text{ V}$
2. B.$4\text{ V}$
3. C.$2\text{ V}$
4. D.$1.5\text{ V}$

Resistance of a wire at $0^{\circ }\text{C},100^{\circ }\text{C}$ and $t^{\circ }\text{C}$ is found to be $10\Omega ,10.2\Omega$ and $10.95\Omega$ respectively. The temperature $t$ in Kelvin scale is ________.

Water boils in an electric kettle in $20\mathrm{minutes}$ after being switched on. Using the same main supply, the length of the heating element should be ____ to ____ times of its initial length if the water is to be boiled in $15\mathrm{minutes}$.

1. A.increased, $\frac{3}{4}$
2. B.increased, $\frac{4}{3}$
3. C.decreased, $\frac{3}{4}$
4. D.decreased, $\frac{4}{3}$