A mirror is inclined at an angle of $\mathrm{\theta }$ with the horizontal. If a ray of light is incident at an angle as shown, then the angle made by reflected ray with the horizontal is $\mathrm{N}\times \mathrm{\theta }.$ The value of N is …………

 According to law of reflection, angle of incidence is equal to angle of reflection. As we can see from diagram, Reflected ray is parallel to horizontal . Hence angle between them is $0^o$. So, the value of N = 0.