Answer:
The focal length of the lens must be 27.3cm
Explanation:
Image distance= -75 cm
Object distance= 20.0cm
From:
1/v + 1/u = 1/f
-1/75+ 1/20 = 1/f
11/300= 1/f
f= 300/11
f= 27.3cm
The focal length of the lens must be 27.3cm

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Answer:
Space radiation is made up of three kinds of radiation: particles trapped in the Earth's magnetic field; particles shot into space during solar flares (solar particle events); and galactic cosmic rays, which are high-energy protons and heavy ions from outside our solar system.
Explanation:
Answer:True
Explanation: The mechanical waves need a medium through which to transport energy because the perturbation travels inside of the medium so it needs molecules that connect elastically the displacement of the wave. For example the sound mainly uses the air molecules to transport the energy also the sound can be traveled in solid materials like metal rods.
The valence electrons are the one furthest from the nucleus