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Calculate the focal length of a corrective lens having power +2D.
Concept: Power of a Lens
A simple microscope is used by watch repairers. Give reason.
Concept: Spherical Mirrors
The distance between principal focus and optical centre of the lens is _________.
- diameter
- focal length
- principal axis
- optical centre
Concept: Images Formed by Sperical Lenses
Draw a ray diagram for concave mirror when the object is between centre of curvature and focus.
Concept: Spherical Mirror > Concave Mirror
In a Std. X class out of 40 students 10 students use spectacles, 2 students have positive power and 8 students have negative power of lenses in their spectacles.
Answer the following questions:
(1) What does the negative power indicate?
(2) What does the positive power indicate?
(3) Generally which type of spectacles do most of the students use?
(4) What defect of eyesight do most of the students suffer from?
(5) Give two possible reasons for the above defect.
Concept: Defects of Vision and Their Corrections > Myopia
With the help of an appropriate ray diagram, state the sign conventions for reflection by a spherical mirror.
Concept: Spherical Mirror > Concave Mirror
Calculate the focal length of a corrective lens having power +2.5 D.
Concept: Power of a Lens
What is myopia?
Concept: Defects of Vision and Their Corrections > Myopia
Explain two possible reasons of myopia. How can it be corrected? Explain with a suitable diagram.
Concept: Defects of Vision and Their Corrections > Myopia
Which type of mirror is used by a dentist?
Concept: Spherical Mirror > Concave Mirror
Define Radius of curvature of the spherical mirror
Concept: Spherical Mirrors
Define the Focal length of a spherical mirror
Concept: Spherical Mirrors
Kavita from 10th is using spectacles. The power of the lenses in her spectacles is –2.5 dioptre. Answer the following questions:
1) Which lenses are used in her spectacles?
2) State the defect of vision Kavita is suffering from.
3) Find the focal length of the lenses used in her spectacles
Concept: Power of a Lens
The height of the image formed by an object of height 10 cm placed in front of a plane mirror is __________.
(a) 5 cm
(b) 10 cm
(c) 15 cm
(d) 20 cm
Concept: Linear Magnification by Spherical Mirrors
An object is held 20 cm away from a converging lens of focal length 10 cm. Find the position of the image formed.
Concept: Magnification
Complete the following table:
| Instrument | Number of Convex Lenses |
Use |
| Simple Microscope | .............. | .............. |
| Compound Microscope | .............. | .............. |
| Telescope | .............. | .............. |
Concept: Convex Lens
i. Which type of microscope has the arrangement of lenses shown in the adjoining figure?
ii. Label the figure correctly.
iii. Write the working of this microscope.
iv. Where does this microscope used?
v. Suggest a way to increase the efficiency of this microscope.
Concept: Convex Lens
The image obtained while finding the focal length of convex lens is ....................
Concept: Convex Lens
Observe the following figure and answer the questions.
a) Which optical instrument shows arrangement of lenses as shown in the figure?
b) Write in brief the working of this optical instrument.
c) How can we get different magnifications in this optical instrument?
d) Draw the figure again and labelled it properly
Concept: Convex Lens
Yesh find out F1 and F2 of symmetric convex lens experimentally then which conclusion is true.
Concept: Convex Lens
