The focal length of the lens is 25cm
given:
power,p=4 diopters
what is focal length?
Focal length is the distance between the point of convergence of your lens and the sensor or film recording the image.
what is diopter?
The unit of optical power of lens is called diopter.It is the optical power of the lens.
we know,
p=1/f
where,
p= power
f= focal length
f=1/p
f=1/4
=0.25m
=25cm
Thus,the focal length of the lens is 25cm
learn more about focal length from here: https/brainly.com/question/28203589
#SPJ4
Answer:
Explanation:
Given
Potential Energy is given by

And Force is given by

Particle will be at equilibrium when Potential Energy is either minimum or maximum

i.e.

So angular Frequency of small oscillation is given by

for 
we get 


Answer:
presumptuous
Explanation:
it's what you call someone who assumes something
D. Advances in technology were needed to gather more evidence.
Explanation:
New technologies had to be developed to ascertain Wegener's claims.
The major flaw in Wegener's postulate was that the moving continents lacked a mechanism to drive them into motion.
His theory needed more scientific backing also.
- A major leap was made when new technologies used during the second world war was deployed to investigate the ocean floor.
- Sequences of magnetic anomalies were unraveled using equipment developed during the second world war
- This gave further proof to the idea of continental drift and it expanded the theory into a more broader and inclusive theory of plate tectonics.
Learn more:
Wegener brainly.com/question/5002949
#learnwithBrainly