Question:
If an optician prescribes a corrective lens of power -2.0 D, the required lens
If an optician prescribes a corrective lens of power -2.0 D, the required lens
Show Hint
A negative power corresponds to a concave lens, and a positive power corresponds to a convex lens.
Updated On: Dec 12, 2025
- is a concave lens.
- is a convex lens.
- has a focal length of +50 cm.
- has a focal length of -50 cm.
Show Solution
Verified By Collegedunia
The Correct Option is A, D
Solution and Explanation
Step 1: Understanding the power of a lens.
The power \( P \) of a lens is related to its focal length \( f \) by the formula: \[ P = \frac{1}{f} \] where \( f \) is in meters and \( P \) is in diopters (D).
Step 2: Analyzing the given power.
For a lens with power \( P = -2.0 \, D \), we can calculate the focal length \( f \): \[ f = \frac{1}{P} = \frac{1}{-2.0} = -0.5 \, \text{m} = -50 \, \text{cm} \] The negative sign indicates that the lens is a concave lens.
Step 3: Conclusion.
The correct answer is:
(A) is a concave lens
(D) has a focal length of -50 cm.
Was this answer helpful?
0
0
Top IIT JAM BT Physics Questions
- Rain is falling vertically with a speed of 40 $m s^{-1}$. Wind starts blowing with a speed of 16 $m s^{-1}$ in the west to east direction. How should a person, who is standing, hold his umbrella to avoid getting wet?
- A massless ideal spring is hanging vertically. A sphere of mass of 500 g, suspended from the spring, stretches the spring from its initial position by 50 cm when it reaches equilibrium. The force constant of the spring is _________ $N m^{-1}$. ($Use g=10 m s^{-2}$)
- Whales can dive undersea to depths of 2 km. The pressure on the whale at this depth (ignoring atmospheric pressure) is _____ $× 10^6 Pa$. (Density of sea water = $1 g cm^{-3}$ and $g =10 m s^{-2}$)
- The heat required to convert 2 kg of water at 20 °C in a calorimeter to steam at 100 °C and at atmospheric pressure (1 atm) is _____ kJ. (Specific heat capacity of water is $4.2 kJ kg^{-1} K^{-1}$ and latent heat of steam is $2256 kJ kg^{-1}$)
- An electron is accelerated from rest through a potential difference of 200 V. The de Broglie wavelength associated with this electron is _____ nm. (Rounded off to 2 decimal places) (Planck’s constant = $6.6 × 10^{-34} J s, 1eV=1.6 × 10^{-19} J$, mass of an electron = $9.1×10^{-31} kg$)
View More Questions
Top IIT JAM BT spherical lenses Questions
- An object is placed at the principal focus of a concave lens of focal length 10 cm. The image will be formed at___ cm, between the optical center and the focus of the lens on the same side of the object.
- A 500 nm light is used for imaging in a confocal microscope. What will be the best resolution (in nm) of this microscope?
- A compound microscope has its objective with linear magnification of 10. In order to achieve a final magnification of 100, the angular magnification of the eyepiece should be ..........
Top IIT JAM BT Questions
- Which one of the following compounds inhibits the polymerization of tubulin to microtubules in animal cells?
- Arrange the following elements in increasing order of their electronegativity according to the Pauling scale
C, Na, Be and Br - Which one of the following is NOT a plant vascular tissue?
- A growing shoot of a germinating seedling encounters an underground obstacle. Which one of the following hormones elicits ‘triple response’ to the underground obstacle?
- Which one of the following pairs of antibodies contains ‘J-chain’ in their multimeric form?
View More Questions