Image formed by a plane mirror is:

1.	real
2.	virtual
3.	depends on the nature of the object
4.	none of these

Two identical equiconvex thin lenses each of focal lengths \(20\) cm, made of material of refractive index \(1.5\) are placed coaxially in contact as shown. Now, the space between them is filled with a liquid with a refractive index of \(1.5\). The equivalent power of this arrangement will be:

A ray of light incident on an equilateral prism at grazing incidence emerges from the prism at grazing emergence. The Refractive index of the prism is:

Two plane mirrors, \(A\) and \(B\) are aligned parallel to each other, as shown in the figure. A light ray is incident at an angle of \(30^\circ\) at a point just inside one end of \(A.\) The plane of incidence coincides with the plane of the figure. The maximum number of times the ray undergoes reflections (excluding the first one) before it emerges out is:
   
1. \(28\)                     
2. \(30\)
3. \(32\)         
4. \(34\)

A rod of glass \((\mu = 1.5)\) and of the square cross-section is bent into the shape as shown. A parallel beam of light falls on the plane's flat surface \(A\) as shown in the figure. If \(d\) is the width of a side and \(R\) is the radius of a circular arc then for what maximum value of \(\frac{d}{R},\) light entering the glass slab through the surface \(A\) will emerge from the glass through \(B?\)

A diverging beam of light from a point source \(S\) having divergence angle \(\alpha,\) falls symmetrically on a glass slab as shown. The angles of incidence of the two extreme rays are equal. If the thickness of the glass slab is \(t\) and the refractive index \(n\), then the divergence angle of the emergent beam is: