The current in an inductor of self-inductance $4~\text{H}$ changes from $4~ \text{A}$ to $2~\text{A}$ in $1~ \text s$. The emf induced in the coil is:
1. $-2~\text{V}$
2. $2~\text{V}$
3. $-4~\text{V}$
4. $8~\text{V}$

The correct statement about the variation of viscosity of fluids with an increase in temperature is:

The de-Broglie wavelength of the thermal electron at $27^\circ \text{C}$ is $\lambda.$ When the temperature is increased to $927^\circ \text{C},$ its de-Broglie wavelength will become:

Assuming the earth to be a sphere of uniform density, its acceleration due to gravity acting on a body:

During simple harmonic motion of a body, the energy at the extreme position is:

A fluid of density $\rho~$is flowing in a pipe of varying cross-sectional area as shown in the figure. Bernoulli's equation for the motion becomes:

1. $p+\dfrac12\rho v^2+\rho gh\text{ = constant}$
2. $p+\dfrac12\rho v^2\text{ = constant}$
3. $\dfrac12\rho v^2+\rho gh\text{ = constant}$
4. $p+\rho gh\text{ = constant}$

The ratio of the moments of inertia of two spheres, about their diameters, having the same mass and their radii being in the ratio of $1:2$, is: