MCQs on Refraction, class 10, Light chapter by Physics Advocate/advguruji

REFRACTION - Multiple Choice Questions

Q1.

The refractive indexes of medium A, B and C are 1.8, 1.6 and 1.7 respectively. Which of them has smallest critical angle?

(i) A

(ii) B

(iii) C

(iv) Insufficient data

Q2.

A convex lens has focal length of 15 cm & forming an erect image. Position of object may be at ____.

(i) 10 cm

(ii) 15 cm

(iii) 20 cm

(iv) 40 cm

Q3.

The refractive index of a medium is 1.2. The speed of light in it is ____ m/s.

(i) 3 × 10⁸

(ii) 2 × 10⁸

(iii) 2.5 × 10⁸

(iv) None of these

Q4.

If the focal length of a lens becomes half, its power becomes ____.

(i) half

(ii) 4 times

(iii) 8 times

(iv) None of these

Q5.

For a convex lens, the distance of image is ____.

(i) positive

(ii) negative

(iii) both (i) & (ii)

(iv) Insufficient data

Q6.

A small bulb is placed at the focal point of a converging lens. When the bulb is switched ON, the lens produces ____.

(i) a convergent beam of light

(ii) a divergent beam of light

(iii) a parallel beam of light

(iv) a patch of coloured light

Q7.

In order to obtain a real image twice the size of the object with a convex lens of focal length 15 cm, the object distance should be ____.

(i) more than 15 cm but less than 30 cm

(ii) more than 5 cm but less than 10 cm

(iii) more than 10 cm but less than 15 cm

(iv) more than 30 cm but less than 60 cm

Q8.

The refractive indexes of four substances P, Q, R and S are 1.75, 1.56, 1.22 and 2.04 respectively. When light travelling in air is incident on these substances at equal angles, the angle of refraction will be maximum in ____.

(i) P

(ii) Q

(iii) R

(iv) S

Q9.

The speed of light in medium X is 2.1 × 10⁸ . Its refractive index with respect to air is ____.

(i) 1.33

(ii) 2.06

(iii) 1.51

(iv) None of these

Q10.

The power of a diverging lens is 10D and a converging lens is 6D. When they are combined together, the effective focal length will be ____.

(i) +25 cm

(ii) -6.25 cm

(iii) +6.25 cm

(iv) -25 cm

Q11.

If a spherical lens has power -0.50D. Its focal length will be ____.

(i) +1 m

(ii) +2 m

(iii) -2 m

(iv) -0.50 m

Q12.

A concave lens always produces ____.

(i) erect & diminished image

(ii) inverted & diminished image

(iii) inverted & enlarged image

(iv) erect & enlarged image

----------------------------------------------------------------------------------------

ANSWERS

ANS1. (i)

ANS2. (i)

ANS3. (iii) ANS4. (iv)

ANS5. (iii)

ANS6. (iii)

ANS7. (i) ANS8. (iii)

ANS9. (iv)

ANS10. (iv)

ANS11. (iii)

ANS12. (i)

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