Are any leptons made of quarks?
1.Yes; leptons are point particles.
2. Yes; leptons have fractional electric
charge.
3. None of these
4. No; leptons have fractional electric
charge.
5. No; leptons are distinct from quarks.

What is the range of electromagnetic force?
1.long range
2.None of these
3.short range
4.very short range

When a star has exhausted its hydrogen fuel,
it may fuse other nuclear fuels, such as helium.
At temperatures above 1.0E8 K, helium fusion can occur. Two alpha particles fuse to
produce a nucleus A and a gamma ray.
What is nucleus A?




Any help appreciated, thanks !

A surface whose work function is Φ = 4.4 eV
is illuminated by a light whose wavelength is
125 nm. What is the maximum kinetic energy of a
photoelectron emitted from the surface?

hf - work function = max K.E.
work = 4.4 eV(1.6E-19C) = 7.04E-19
f = (3E8)/(125E-4) = 2.4E10
(6.63E-34)(2.4E10) - (7.2E-19) = -7.1998409E-19

Doesn't seem to be right though, since it's a negative value.
Can anyone help look it over?

Got #1/2/3/16 done.

Also need help on this problem:

A metal has work function 4.9 eV.
What is the kinetic energy of a photoelectron if radiation of wavelength 190 nm falls
on the surface of the metal? The value of hc is 1240 eV x nm.
Answer in units of eV

This post was edited by Sefira on May 25 2013 11:24am

Got post #2's question done.

Need last one.

Done, thanks for the help Sefira

I guessed on #14, so I'm still needing a bit of help on that.

Would appreciate it if anyone's able to explain to me.