On heating one end of a rod, the temperature of whole rod will be uniform when

A copper rod and a steel rod of equal cross-sections and lengths $(L)$ are joined side by side and connected between two heat baths as shown in the figure

If heat flows through them from $x = 0$ to $x = 2L$ at a steady rate and conductivities of the metals are $K_{cu}$ and $K_{steel}$ $(K_{cu} > K_{steel}),$ then the temperature varies as (convection and radiation are negligible)

Two identical plates of different metals are joined to form a single plate whose thickness is double the thickness of each plate. If the coefficients of conductivity of each plate are $2$ and $3$ respectively, then the conductivity of composite plate will be

he ratio of the coefficient of thermal conductivity of two different materials is $5 : 3$ . If the thermal resistance of the rod and thickness of these materials is same, then the ratio of the length of these rods will be

Bottom of a lake is at $0^{\circ} C$ and atmospheric temperature is $-20^{\circ} C$. If $1 cm$ ice is formed on the surface in $24 \,h$, then time taken to form next $1 \,cm$ of ice is ......... $h$

Which of the following circular rods. (given radius $ r$ and length $l$ ) each made of the same material as whose ends are maintained at the same temperature will conduct most heat