No particle can ever move at a speed greater than that of light in vacuum.
  • True
  • False
A ray of light goes from a medium of refractive index${{n}_{_{1}}}$ to a medium of refractive index ${{n}_{2}}$. the angle of incidence is $i$ and the angle of refraction is $r$. Then, $\frac{sin i}{sin r}$ is equal to
  • $\frac{n_2}{n_1}$
  • $\frac{n_1}{n_2}$
  • ${{n}_{2}}$
  • ${{n}_{1}}$
A lens has a power of $+0.5 D$. it is
  • a concave lens of focal length 2m
  • a convex lens of focal length 2m
  • a convex lens of focal length 5cm
  • a concave lens of focal length 5cm
The value of $f$ and $u$ for a concave lens are always negative by convention.
  • True
  • False
When two lenses are placed in contact, the focal length of the combination is equal to the sum of the focal lengths of the lenses.
  • True
  • False
A ray of light travelling in air falls obliquely on the surface of a calm pond. It will
  • deviate towards the normal
  • go into the water without deviating from its path
  • deviate away from the normal
  • turn back of its original path
If a ray of light passes from vacuum to a transparent medium, it will bend away from the normal.
  • True
  • False
The central portion of a thin lens behaves like a rectangular slab
  • True
  • False
A convex lens forms a virtual image when an object is placed at a distance of 18cm from it. The focal length must be
  • less than 36cm
  • greater than 36cm
  • greater than 18cm
  • less than 18cm
A thin lens and a spherical mirror have a focal length of $+15cm$ each.
  • Both are concave
  • Both are convex.
  • The lens is convex and the mirror is concave
  • The lens is concave and the mirror is convex
An object is placed before a concave lens. The image formed
  • is always erect
  • is always real
  • is always inverted
  • may be erect or inverted
The angle of reflection is the angle between
  • the normal to the surface and reflected ray.
  • the reflected ray and the surface of the mirror
  • (i) and (ii)
  • None of the above
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