Two solid conductors are made of the same material,have the same length,and have the same resistance. One of them has a circular cross-section of area $A_{1}$ and the other has a square cross-section of area $A_{2}$. The ratio $\frac{A_{1}}{A_{2}}$ is

Three copper wires of lengths and cross-sectional areas are $(l, A)$,$(2l, A/2)$,and $(l/2, 2A)$. Resistance is minimum in

The resistance of a wire of uniform diameter $d$ and length $L$ is $R$. The resistance of another wire of the same material but diameter $2d$ and length $4L$ will be

The resistance of a tungsten wire at $150^{\circ} C$ is $133 \Omega$. The temperature coefficient of resistance is $0.0045^{\circ} C^{-1}$. The resistance of this wire at $500^{\circ} C$ is: (in $Omega$)

The figure shows a rectangular block with dimensions $x, 2x$ and $4x$. Electrical contacts can be made to the block between opposite pairs of faces (for example,between the faces labelled $A-A, B-B$ and $C-C$). Between which two faces would the maximum electrical resistance be obtained? ($A-A$: Top and bottom faces,$B-B$: Left and right faces,$C-C$: Front and rear faces)

The resistance of a wire is $20 \, \Omega$. It is stretched such that its length becomes three times its original length. The new resistance of the wire will be ............. $ \Omega$.