An electron in Hydrogen atom jumps from the second Bohr orbit to the ground state and the difference between the energies of the two states is radiated in the form of a photon. This photon strikes a material. If the work function of the material is 4.2 eV , then the stopping potential is (Energy of electron in $n$-th orbit $\left.=-\frac{13 \cdot 6}{n^2} \mathrm{eV}\right)$
A ball falls from a height $h$ upon a fixed horizontal floor. The co-efficient of restitution for the collision between the ball and the floor is ' $e$ '. The total distance covered by the ball before coming to rest is [neglect the air resistance]
Manufacturers supply a zener diode with zener voltage $\mathrm{V}_{\mathrm{z}}=5.6 \mathrm{~V}$ and maximum power dissipation $P_{\mathrm{z}, \max }=\frac{1}{4} \mathrm{~W}$. This zener diode is used in the following circuit. Calculate the minimum value of the resistance $R_s$ in the circuit so that the zener diode will not burn when the input voltage is $\mathrm{V}_{\mathrm{in}}=10 \mathrm{~V}$.
A force $\vec{F}=a \hat{i}+b \hat{j}+c \hat{k}$ is acting on a body of mass $m$. The body was initially at rest at the origin. The co-ordinates of the body after time ' $t$ ' will be