Question:
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.
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.
Updated On: Nov 27, 2025
Show Solution
Verified By Collegedunia
Correct Answer: 5
Solution and Explanation
When dealing with lenses, the lens formula is given by: 1/f = 1/v - 1/u, where f is the focal length, v is the image distance, and u is the object distance. For a concave lens, the focal length is negative. Here, f = -10 cm, and the object is placed at the focus, hence u = -10 cm (object distances are also negative in lens equations).
Substituting in the lens formula: 1/(-10) = 1/v - 1/(-10). Simplifying gives:
1/(-10) = 1/v + 1/10
Bring similar terms together:
1/v = 1/(-10) - 1/10
1/v = -1/10 - 1/10 = -2/10 = -1/5
Thus, v = -5 cm. The negative sign confirms that the image is virtual and forms on the same side as the object.
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
- 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 ..........
- If an optician prescribes a corrective lens of power -2.0 D, the required lens
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