Light Reflection and Refraction- 1Mark Questions Revision

1) What is the unit of power of lens

• dioptre
• Frequency

• millimeters

• meters

2) which of the following is the use of convex lens

• door peep holes

• binoculars

• telescope
• microscope

3) 4 important characteristics of image formed by plane mirror

• Virtual image
• Erect
• Laterally inverted
• Same size as object
• Real image

4) A concave mirror gives real, inverted and same size image if the object is placed at

• At F

• At infinity

• At C

• Beyond C

5) The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object?

• Between the pole of the mirror and its principal focus.
• Between the principal focus and the centre of curvature
• At the centre of curvature
• Beyond the centre of curvature

6) Where should an object be placed in front of a convex lens to get a real image of the size of the object?

• Between the optical centre of the lens and its principal focus
• At twice the focal length
• At the principal focus of the lens
• At infinity

7) A spherical mirror and a thin spherical lens have a focal length of -15 cm. The mirror and the lens are likely to be

• both convex
• the mirror is convex, but the lens is concave
• both concave
• the mirror is concave and the lens is convex

8) Find the focal length of a lens of power +2.5 D. The focal length in cm will be....

• +40

• -40

• +80

• -80

9) A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

• convex lens
• concave lens
• diverging lens
• converging lens

10) The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

• 10cm
• 12 cm
• 20 cm
• 5cm