If a real and inverted image is formed by a convex lens on a screen 20 cm away from the lens, and the object is placed 30 cm from the lens, what is the focal length of the lens according to the lens formula?
The focal length is 12 cm
Convex lens: object distance u = −30 cm, image distance v = +20 cm (real image on screen).
Lens formula: \(\frac{1}{f} = \frac{1}{v} - \frac{1}{u} = \frac{1}{20} - \frac{1}{-30} = \frac{1}{20} + \frac{1}{30}\).
\(\frac{1}{f} = \frac{3 + 2}{60} = \frac{5}{60} = \frac{1}{12}\).
So f = 12 cm.
Hence, The focal length is 12 cm.
Similar Questions
If a bulb is designed to work at 12 volts and 0.5 amperes, what should be the resistance of the filament according to Ohm's Law?
A car of mass 1000 kg moves with a velocity of 20 m/s. The kinetic energy of the car is _______________.
According to Rutherford's model, where is most of the mass of an atom concentrated?
Which of the following best describes the path of a light ray as it enters and then exits a glass slab from air?
If the frequency of a sound wave is 10 Hz, its time period is:
A ball of mass 0.5 kg is accelerated at 4 m/s2. If a second ball of mass 1 kg is to achieve the same acceleration, what force must be applied to it?
A box is pushed with a force of 20 N across a horizontal floor for a distance of 5 m in the direction of the force. What is the work done by the force?
In a scenario where light passes through three different media (air, water, and glass) in sequence, which law helps in predicting the final direction of the light ray?
What is the size of the image produced by a concave lens compared to the object?
A student observes a body moving with constant speed along a circular path. Which of the following best represents the graphical relationship between its speed and time for one complete revolution?
Important Questions from Physics
What is the colour of the light emitted by the Sun?
Lightning occur in the sky when two clouds:
With reference to street-lighting, how do sodium lamps differ from LED lamps?
1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.
2. As street lights, sodium lamps have a longer life span than LED lamps.
3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street lighting.
Select the correct answer using the code given below.
In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
1. Area of the hole in the lid
2. Temperature of the flame
3. Weight of the lid
Select the correct answer using the code given below.
The famous phenomenon 'Raman Effect' discovered by Nobel laureate CV Raman is related to which field of physics?
