A proton moving with a momentum $P_1$ has a kinetic energy ${\left(\frac{1}{8}\right)}^{th}$ of its rest mass energy. Another light photon having energy equal to the kinetic energy of the proton possesses a momentum $P_2.$ Then the ratio $\frac{P_1-P_2}{P_1}$ is equal to

The following graph represents the variation of photo current with anode potential for a metal surface. Here $I_1, I_2$ and $I_3$ represents intensities and ${\gamma }_1,{\gamma }_2,{\gamma }_3$ represents frequency for curves $1, 2$ and $3$ respectively, then

The figure shows standing de Broglie waves due to the revolution of electron in a certain orbit of hydrogen atom. Then the expression for the orbit radius is (all notations have their usual meanings)