A person has near point at 100cm.
Question: A person has near point at $100 \mathrm{~cm}$. What power of lens is needed to read at $20 \mathrm{~cm}$ if he/she uses (a) contact lens, (b) spectacles having glasses 2 ' $0 \mathrm{~cm}$ separated from the eyes? Solution:...
Read More →A nearsighted person cannot see beyond
Question: A nearsighted person cannot see beyond $25 \mathrm{~cm}$. Assuming that the separation of the glass from the eye is $1 \mathrm{~cm}$, find the power of lens needed to see distant objects. Solution:...
Read More →The near point and the far point of a child are
Question: The near point and the far point of a child are at $10 \mathrm{~cm}$ and $100 \mathrm{~cm}$. If the retina is $2.0 \mathrm{~cm}$ behind the eyelens, what is the range of the power of the eye-lens? Solution:...
Read More →A normal eye has retina 2 cm
Question: A normal eye has retina $2 \mathrm{~cm}$ behind the eye-lens. What is the power of the eye-lens when the eye is (a) fully relaxed (b) most strained? Solution:...
Read More →A professor reads a greeting card received on his 50 th birthday with
Question: A professor reads a greeting card received on his 50 th birthday with $+2.5 \mathrm{D}$ glasses keeping the card $25 \mathrm{~cm}$ away. Ten years later, he reads his farewell letter with the same glasses but he has 'to keep the letter $50 \mathrm{~cm}$ away. What power of lens should he now use? Solution:...
Read More →A person wears glasses of power - 2.5 D.
Question: A person wears glasses of power - $2.5 \mathrm{D}$. Is the person farsighted or nearsighted? What is the far point of the person without the glasses? Solution:...
Read More →A nearsighted person cannot clearly see beyond
Question: A nearsighted person cannot clearly see beyond $200 \mathrm{~cm}$. Find the power of the lens needed to see objects at large distance? Solution:...
Read More →A farsighted person cannot see objects placed closer to
Question: A farsighted person cannot see objects placed closer to $50 \mathrm{~cm}$. Find the power of the lens needed to see the objects at $20 \mathrm{~cm}$. Solution:...
Read More →A Galilean telescope is 27 cm long
Question: A Galilean telescope is $27 \mathrm{~cm}$ long when focused to form an image at infinity. If the objective has a focal length of $30 \mathrm{~cm}$, what is the focal length of the eyepiece? Solution:...
Read More →The eyepiece of an astronomical telescope has a focal length of
Question: The eyepiece of an astronomical telescope has a focal length of $10 \mathrm{~cm}$. The telescope is focused for normal vision of distant objects when the tube length is $1.0 \mathrm{~m}$. Find the focal length of the objective and the magnifying power of the telescope. Solution:...
Read More →An astronomical telescope is to be designed to have a magnifying power
Question: An astronomical telescope is to be designed to have a magnifying power of 50 in normal adjustment. If the length of the tube is $102 \mathrm{~cm}$, find the powers of the objective and the eyepiece. Solution:...
Read More →An optical instrument used for angular magnification
Question: An optical instrument used for angular magnification has a 25 D objective and a 20 D eyepiece. The tube length is $25 \mathrm{~cm}$ when the eye is least strained. (a) Whether it is a microscope or a telescope? (b) What is the angular magnification produced? Solution:...
Read More →An optical instrument used for angular magnification
Question: An optical instrument used for angular magnification has a 25 D objective and a 20 D eyepiece. The tube length is $25 \mathrm{~cm}$ when the eye is least strained. (a) Whether it is a microscope or a telescope? (b) What is the angular magnification produced? Solution:...
Read More →A compound microscope consists of an objective of
Question: A compound microscope consists of an objective of focal length $1 \mathrm{~cm}$ and an eyepiece of focal length $5 \mathrm{~cm}$. An object is placed at a distance of $0.5 \mathrm{~cm}$ from the objective. What should be the separation between the lenses so that the microscope projects an inverted real image of the object on a screen $30 \mathrm{~cm}$ behind the eyepiece? Solution:...
Read More →A compound microscope has a magnifying power of 100
Question: A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of $0.5 \mathrm{~cm}$ and the tube length is $6.5 \mathrm{~cm}$. Find the focal length of the eyepiece. Solution:...
Read More →An eye can distinguish between two points
Question: An eye can distinguish between two points of an object if they are separated by more than $0.22 \mathrm{~mm}$ when the object is placed at $25 \mathrm{~cm}$ from the eye. The object is now seen by a compound microscope having a 20 D objectives and 10 D eyepiece separated by a distance of $20 \mathrm{~cm}$. The final image is formed at $25 \mathrm{~cm}$ from the eye. What is the minimum separation between two points of the object which can now be distinguished? Solution:...
Read More →The separation between the objective and
Question: The separation between the objective and the eyepiece of a compound microscope can be adjusted between $9.8 \mathrm{~cm}$ to $11 ' 8 \mathrm{~cm}$. If the focal lengths of the objective and the eyepiece are 1 ' $0 \mathrm{~cm}$ and $6 \mathrm{~cm}$ respectively, find the range of the magnifying power if the image is always needed at $24 \mathrm{~cm}$ from the eye. Solution:...
Read More →Find the maximum magnifying power of a compound Microscope
Question: Find the maximum magnifying power of a compound Microscope having a 25 diopter lens as the objective, a 5 diopter lens as the eyepiece and the separation $30 \mathrm{~cm}$ between the two lenses. The least distance for clear vision is $25 \mathrm{~cm}$. Solution:...
Read More →A simple microscope is rated 5 X
Question: A simple microscope is rated $5 X$ for a normal relaxed eye. What will be its magnifying power for a relaxed farsighted eye whose near point is $40 \mathrm{~cm}$ ? Solution:...
Read More →A child has near point at 10 cm.
Question: A child has near point at $10 \mathrm{~cm}$. What is the maximum angular magnification the child can have with a convex lens of focal length $10 \mathrm{~cm}$ ? Solution:...
Read More →A simple microscope has a magnifying power of
Question: A simple microscope has a magnifying power of $3^{\prime} 0$ when the image is formed at the near point ( $\left.25 \mathrm{~cm}\right)$ of a normal eye. (a) What is its focal length? (b) What will be its magnifying power if the image is formed at infinity? Solution:...
Read More →An object is to be seen through a simple microscope of
Question: An object is to be seen through a simple microscope of focal length $12 \mathrm{~cm}$. Where the object should be placed so as to produce maximum angular magnification? The least distance for clear vision is $25 \mathrm{~cm}$. Solution:...
Read More →A person looks at different trees in an open space with
Question: A person looks at different trees in an open space with the following details. Arrange the trees in decreasing order of their apparent sizes. Solution:...
Read More →Consider the situation shown in figure (18-E16).
Question: Consider the situation shown in figure (18-E16). The elevator is going up with an acceleration of $2.00 \mathrm{~m} / \mathrm{s}^{2}$ and the focal length of the mirror is $12.0 \mathrm{~cm}$. all the surfaces are smooth and the pulley is light. The mass pulley system is released from rest (with respect to the elevator) at $i=0$ when the distance of $B$ from the mirror is $42 \mathrm{~cm}$. Find the distance the image of the block B and the mirror at $t=0.200 \mathrm{~s}$. Take $\mathr...
Read More →Two concave mirrors of equal radi of curvature R
Question: Two concave mirrors of equal radi of curvature $R$ are fixed on a stand facing opposite directions. The whole system has a mass $m$ and is kept on a frictionless horizontal table (fig.) Two block $A$ and $B$ each mass $m$, are placed on the two sides of the stand $A t d=0$, the separation between $\mathrm{A}$ and the mirror is $2 \mathrm{R}$ and also the separation between $\mathrm{B}$ and the mirror is $2 \mathrm{R}$. The block B moves towards the mirror at a speed v. All collisions w...
Read More →