Answer:
20cm
Explanation:
A convex lens has a positive focal length and the object placed in front of it produce both virtual and real image <em>(image distance can be negative or positive depending on the nature of the image</em>).
According to the lens equation
where;
f is the focal length of the lens
u is the object distance
v is the image distance
If the magnification is - 0.6
mag = v/u = -0.5
v = -0.5u
since v = 10cm
10 = -0.5u
u = -10/0.5
u =-20 cm
Substitute u = -20cm ( due to negative magnification)and v = 10cm into the lens formula to get the focal length f

Hence the focal length of the convex lens is 20cm
Photons are particles of electromagnetic radiation.
Hello,
Your answer to this problem is 400/3
Hope this helps!
Answer:
the longest wavelength of incident sunlight that can eject an electron from the platinum is 233 nm
Explanation:
Given data
Φ = 5.32 eV
to find out
the longest wavelength
solution
we know that
hf = k(maximum) +Ф ...............1
here we consider k(maximum ) will be zero because photon wavelength max when low photon energy
so hf = 0
and hc/ λ = +Ф
so λ = hc/Ф ................2
now put value hc = 1240 ev nm and Φ = 5.32 eV
so hc = 1240 / 5.32
hc = 233 nm
the longest wavelength of incident sunlight that can eject an electron from the platinum is 233 nm