Current Electricity

In a potentiometer arrangement, a cell gives a balancing point at 75 cm length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is 3 : 2, the difference in the balancing length of the potentiometer wire in above two cases will be ______ cm.

What will be the most suitable combination of three resistors A $=2\ \Omega$, B $=4\ \Omega$, C $=6\ \Omega$ so that $\left(\dfrac{22}3\right)\Omega$ is equivalent resistance of combination?

A potentiometer wire of length 10 m and resistance $20\ \Omega$ is connected in series with a 25 V battery and an external resistance $30\ \Omega$. A cell of emf E in secondary circuit is balanced by 250 cm long potentiometer wire. The value of E (in volt) is $\dfrac x{10}$. The value of $x$ is ______.

A resistor develops 300 J of thermal energy in 15 s, when a current of 2 A is passed through it. If the current increases to 3 A, the energy developed in 10 s is ______ J.

The total current supplied to the circuit as shown in figure by the 5 V battery is ______ A.

Two cells of same emf but different internal resistances $r_1$ and $r_2$ are connected in series with a resistance $R$. The value of resistance $R$, for which the potential difference across second cell is zero, is :

If $n$ represents the actual number of deflections in a converted galvanometer of resistance $G$ and shunt resistance $S$. Then the total current $I$ when its figure of merit is $K$ will be :

The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be ______%.

An aluminium wire is stretched to make its length, 0.4% larger. The percentage change in resistance is :

As per the given circuit, the value of current through the battery will be ______ A.

The equivalent resistance between points A and B in the given network is :

A $72\ \Omega$ galvanometer is shunted by a resistance of $8\ \Omega$. The percentage of the total current which passes through the galvanometer is :

A 220 V, 50 Hz AC source is connected to a 25 V, 5 W lamp and an additional resistance R in series (as shown in figure) to run the lamp at its peak brightness, then the value of R (in ohm) will be ______.

A cell, shunted by a $8\ \Omega$ resistance, is balanced across a potentiometer wire of length 3 m. The balancing length is 2 m when the cell is shunted by $4\ \Omega$ resistance. The value of internal resistance of the cell will be ______ $\Omega$.

The current density in a cylindrical wire of radius 4 mm is $4\times10^6$ Am$^{-2}$. The current through the outer portion of the wire between radial distances $\dfrac R2$ and R is ______ $\pi$ A.

The current density in a cylindrical wire of radius $r=4.0$ mm is $1.0\times10^6$ A/m$^2$. The current through the outer portion of the wire between radial distances $\dfrac r2$ and $r$ is $x\pi$ A; where $x$ is ______.

In the given circuit 'a' is an arbitrary constant. The value of $m$ for which the equivalent circuit resistance is minimum, will be $\sqrt{\dfrac x2}$. The value of $x$ is ______.

The cut-off voltage of the diodes (shown in figure) in forward bias is 0.6 V. The current through the resister of 40 $\Omega$ is ______ mA.

A meter bridge setup is shown in the figure. It is used to determine an unknown resistance R using a given resistor of 15 $\Omega$. The galvanometer (G) shows null deflection when tapping key is at 43 cm mark from end A. If the end correction for end A is 2 cm, then the determined value of R will be ______ $\Omega$.

Current measured by the ammeter (A) in the reported circuit when no current flows through 10 $\Omega$ resistance, will be ______ A.