Current Electricity · JEE Main previous year questions

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

1. A.0.04 V/cm
2. B.0.01 V/cm
3. C.0.02 V/cm
4. D.0.03 V/cm

1. A.4 A
2. B.2 A
3. C.zero
4. D.0.4 A

1. A.$A.B$
2. B.$\bar{A}+\bar{B}$
3. C.$\bar{A}.\bar{B}$
4. D.$\mathrm{A}+\mathrm{B}$

The length of a potentiometer wire is 1200 cm and it carries a current of 60 mA. For a cell of emf 5V and internal resistance of $20\Omega$, the null point on it is found to be a 1000 cm. The resistance of whole wire is :

1. A.$80\Omega$
2. B.$60\Omega$
3. C.$120\Omega$
4. D.$100\Omega$

Four resistances of $15\Omega$, $12\Omega$, $4\Omega$ and $10\Omega$ are connected respectively in cyclic order to form Wheatstone's network. The resistance that is to be connected in parallel with the resistance of $10\Omega$ to balance the network is _______$\Omega$.

A galvanometer having a coil resistance $100\Omega$ gives a full scale deflection when a current of 1 mA is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter giving full scale deflection for a potential difference of 10 V?

1. A.$8.9\text{ k}\Omega$
2. B.$10\text{ k}\Omega$
3. C.$9.9\text{ k}\Omega$
4. D.$7.9\text{ k}\Omega$

1. A.$\frac{\epsilon L}{e{R}^2}$
2. B.$\frac{\epsilon L}{R^2}$
3. C.$\frac{\epsilon L}{R^2}\left(1-\frac{1}{e}\right)$
4. D.$\frac{\epsilon R}{e{L}^2}$

1. A.toggles between 0 and 1
2. B.1
3. C.will not execute
4. D.0

The series combination of two batteries, both of the same emf 10 V, but different internal resistance of $20\Omega$ and $5\Omega$, is connected to the parallel combination of two resistors $30\Omega$ and $R\Omega$. The voltage difference across the battery of internal resistance $20\Omega$ is zero, the value of R (in $\Omega$) is : _______

1. A.0.4
2. B.0.25
3. C.0.2
4. D.0.5

An emf of 20 V is applied at time t = 0 to a circuit containing in series 10 mH inductor and $5\Omega$ resistor. The ratio of the currents at time $\text{t}=\infty$ and at $\text{t}=40\text{ s}$ is close to : (Take $e^2=7.389$)

1. A.1.06
2. B.0.84
3. C.1.15
4. D.1.46

The balancing length for a cell is 560 cm in a potentiometer experiment. When an external resistance of $10\Omega$ is connected in parallel to the cell, the balancing length changes by 60 cm. If the internal resistance of the cell is $\frac{N}{10}\Omega$, where N is an integer then value of N is .............

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

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

1. A.$115\mu \text{A}$
2. B.$170\mu \text{A}$
3. C.$60\mu \text{A}$
4. D.$150\mu \text{A}$

1. A.The value of the resistance R is $1.5\Omega$
2. B.The emf of the battery is 1.5 V and its internal resistance is $1.5\Omega$
3. C.The emf of the battery is 1.5 V and the value of R is $1.5\Omega$
4. D.The potential difference across the battery is 1.5 V when it sends a current of 1000 mA

1. A.$5\times 10^4$, $5\times 10^5$
2. B.$5\times 10^4$, $5\times 10^6$
3. C.$5\times 10^4$, $2.5\times 10^6$
4. D.$2.5\times 10^4$, $2.5\times 10^6$

1. A.$\frac{2.7EL}{R^2}$
2. B.$\frac{EL}{2.7R^2}$
3. C.$\frac{7.3EL}{R^2}$
4. D.$\frac{EL}{7.3R^2}$

A moving coil galvanometer, having a resistance G, produces full scale deflection when a current Ig flows through it. This galvanometer can be converted into (i) an ammeter of range 0 to $I_0(I_0>I_g)$ by connecting a shunt resistance $R_A$ to it and (ii) into a voltmeter of range 0 to V $(V=G{I}_0)$ by connecting a series resistance $R_V$ to it. Then,

1. A.$R_A{R}_V=G^2$ and $\frac{R_A}{R_V}=\frac{I_g}{(I_0-I_g)}$
2. B.$R_A{R}_V=G^2\left(\frac{I_g}{I_0-I_g}\right)$ and $\frac{R_A}{R_V}={\left(\frac{I_0-I_g}{I_g}\right)}^2$
3. C.$R_A{R}_V=G^2\left(\frac{I_0-I_g}{I_g}\right)$ and $\frac{R_A}{R_V}={\left(\frac{I_g}{I_0-I_g}\right)}^2$
4. D.$R_A{R}_V=G^2$ and $\frac{R_A}{R_V}={\left(\frac{I_g}{I_0-I_g}\right)}^2$

A current of 5 A passes through a copper conductor (resistivity $=1.7\times 10^{-8}\Omega \mathrm{m}$) of radius of cross-section 5 mm. Find the mobility of the charges if their drift velocity is $1.1\times 10^{-3}m/s$.

1. A.$1.3{\mathrm{m}}^2/Vs$
2. B.$1.0{\mathrm{m}}^2/Vs$
3. C.$1.8{\mathrm{m}}^2/Vs$
4. D.$1.5{\mathrm{m}}^2/Vs$

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