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Selina solutions concise physics class 8 icse Solutions for Chapter 5 light energy

Exercises in Chapter 5 light energy Grade 8
Questions in Objective Questions

Q4) Select the correct alternative :

(a) The speed of light in air or vacuum is

  1. 3\times10^{8\ }ms^{-1}

  2. 2.25\times10^{8\ }ms^{-1}

  3. 332ms^{-1}

  4. 2.0\times10^{8\ }ms^{-1}

(b) A ray of light moving from an optically rarer to a denser medium

  1. bends away from the normal

  2. bends towards the normal

  3. remains undeviated

  4. none of the above

(c) The angle between the normal and refracted ray is called

  1. angle of deviation

  2. angle of incidence

  3. angle of refraction

  4. the angle of emergence

(d) The property of splitting of white light into its seven constituent colours is known as

  1. rectilinear propagation

  2. refraction

  3. reflection

  4. dispersion

(e) The seven colours in the spectrum of sunlight in order, are represented as:

  1. VIBGYOR

  2. VIGYBOR

  3. BIVGYOR

  4. RYOBIVG

(f) A ray of light passing through centre of curvature of a spherical mirror, after reflection

  1. passes through the focus

  2. passes through the pole

  3. becomes parallel to the principal axis

  4. retraces its own path

(g) If the radius of curvature of a concave mirror is 20 cm, its focal length is:

  1. 10 cm

  2. 20 cm

  3. 40 cm

  4. 80 cm

(h) The image formed by a convex mirror is

  1. erect and diminished

  2. erect and enlarged

  3. inverted and diminished

  4. inverted and enlarged

(i) The image formed by a concave mirror is of the same size as the object, if the object is placed

  1. at the focus

  2. between the pole and focus

  3. between the focus and centre of curvature

  4. at the center of curvature

(j) A convex mirror is used

  1. as a shaving mirror

  2. as a head mirror by a dentist

  3. as a rear view mirror by a driver

  4. as a reflector in torch

Questions in Short/Long Answer Questions
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