In series LCR circuit, the capacitance is changed from $C$ to $4 C$. To keep the resonance frequency unchanged, the new inductance should be:

A particle moving in a circle of radius $\mathrm{R}$ with uniform speed takes time $\mathrm{T}$ to complete one revolution.

If this particle is projected with the same speed at an angle $\theta$ to the horizontal, the maximum height attained by it is equal to $4 R$. The angle of projection $\theta$ is then given by :

With rise in temperature, the Young's modulus of elasticity :

In the given circuit if the power rating of Zener diode is $10 \mathrm{~mW}$, the value of series resistance $R_s$ to regulate the input unregulated supply is :