**Question:**

In a meter bridge experiment resistances are connected as shown in the figure. Initially resistance $\mathrm{P}=4 \Omega$ and the neutral point $\mathrm{N}$ is at $60 \mathrm{~cm}$ from $\mathrm{A}$. Now an unknown resistance $R$ is connected in series to $P$ and the new position of the neutral point is at $80 \mathrm{~cm}$ from $\mathrm{A}$. The value of unknown resistance $\mathrm{R}$ is :

Correct Option: 4

**Solution:**

### Related Questions

A circuit to verify Ohm’s law uses ammeter and voltmeter in series or parallel connected correctly to the resistor. In the circuit:

Consider four conducting materials copper, tungsten, mercury and aluminium with resistivity $\rho_{C}, \rho_{T}, \rho_{M}$ and $\rho_{A}$ respectively. Then :

To verify Ohm’s law, a student connects the voltmeter across the battery as, shown in the figure. The measured voltage is plotted as a function of the current, and the following graph is obtained :

If $\mathrm{V}_{\mathrm{o}}$ is almost zero, identify the correct statement:

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

In an experiment, the resistance of a material is plotted as a function of temperature (in some range). As shown in the figure, it is a straight line.

One may canclude that:

Space between two concentric conducting spheres of radii $a$ and $b(b>a)$ is filled with a medium of resistivity $\rho$. The resistance between the two spheres will be :

In a conductor, if the number of conduction electrons per unit volume is $8.5 \times 10^{28} \mathrm{~m}^{-3}$ and mean free time is $25 f s$ (femto second), it’s approximate resistivity is $\left(\mathrm{m}_{0}=9.1 \times 10^{-31} \mathrm{~kg}\right)$

A $200 \Omega$ resistor has a certain color code. If one replaces the red color by green in the code, the new resistance will be :

The charge on a capacitor plate in a circuit, as a function of time, is shown in the figure:

What is the value of current at $\mathrm{t}=4 \mathrm{~s}$ ?

A resistance is shown in the figure. Its value and tolerance are given respectively by: