Potential gradient of potentiometer is obtained at 6 m and 2 m when two cells are joined in series in (i) helping condition (ii) opposing condition respectively. So ratio of emf of cells is _____

Unit of potential gradient is _____

For two wires of the same material ratio of their mass is 1 : 2 and ratio of their length is 2 : 1. So ratio of their resistances is _____

The resistance of copper wire at 0ºC will be four times at _____ ºC temperature (For copper temperature co-efficient of resistance = 4 x 10^-3 ºC^-1)

Equivalent resistance of parallel combination of two wires is $\frac{6}{5}$ Ω. If one wire is broken resistance becomes 2Ω so resistance of broken wire = _____ Ω.

The current through a wire varies with time as I = I₀ + αt, where I₀ = 10 A and α = 4 As^-1. The charge that flows across a cross-section of the wire in first 10 seconds is _____

The current density along the axis of a cylindrical conductor having radius equal to R is given by $\mathrm{J}={\mathrm{J}}_0\left(1-\frac{r^2}{{\mathrm{R}}^2}\right)$. The current along the length of the conductor is _____ . The distance from the axis is given by r.

A copper wire is stretched to make it 0.1% longer. The percentage change in its resistance is _____ . [Assume that the volume of the wire remains constant.]

The resistance of the platinum wire of a platinum resistance thermometer at the ice-point is 5 Ω and at steam point is 5.23 Ω. When the thermometer is inserted in a hot bath, the resistance of the platinum wire is 5.795 Ω. The temperature of the bath is _____

Two materials have the value of α₁ and α₂ as 6 x 10^-4(ºC)^-1 and -5 x 10^-4(ºC)^-1 respectively. The resistivity of the first material ρ₂₀ = 2 x 10^-8 Ωm. A new material is made by combining the above two materials. The resistivity does not change with temperature. The resistivity ρ₂₀ of the second material is _____ . Considering the reference temperature as 20ºC assume that the resistivity of the new material is equal to the sum of the resistivity of its component materials.