The colour code for a carbon resistor of resistance $0.25\mathrm{k\Omega }\pm 10\%$ is

The colour coding on a carbon resistor is shown in the given figure. The resistance value of the given resistor is:

In the given circuit the internal resistance of the $18 \mathrm{V}$ cell is negligible. If $R_1=400 \mathrm{\Omega }, R_3=100 \mathrm{\Omega }$ and $R_4=500 \mathrm{\Omega }$ and the reading of an ideal voltmeter across $R_4$ is $5 \mathrm{V},$ then the value $R_2$ will be

In the shown arrangement of the experiment of the meter bridge if the length $AC$ corresponding to null deflection of galvanometer is $x,$ what would be its value if the radius of the wire $AB$ is doubled?

A meter bridge is set-up as shown, to determine an unknown resistance $\text{'}X\text{'}$ using a standard $10 \mathrm{ohm}$ resistor. The galvanometer shows null point when tapping-key is at $52 \mathrm{cm}$ mark. The end-corrections are $1 \mathrm{cm}$ and $2 \mathrm{cm}$ respectively for the ends $\mathrm{A}$ and $\mathrm{B}$. The determined value of ${\mathrm{X}}^{\text{'}}$ is: