An electron and a positron, both essentially at rest, annihilate each other, emitting two identical photons in the process
What is the wavelength of these photons? The mass of an electron or positron is 9.11 × 10-31 kg. (h = 6.626 × 10-34 J ? s, c = 3.00 × 108 m/s)
A) 3.07 pm
B) 1.21 × 10-12 pm
C) 2.42 pm
D) 1.73 pm
E) 3.46 pm
C
You might also like to view...
A piece of plastic has a net charge of +2.00 ?C. How many more protons than electrons does this piece of plastic have?
A) 1.25 × 1013 B) 1.25 × 1019 C) 2.50 × 1013 D) 2.50 × 1019 E) 0
A ray of light enters an equilateral prism made of material with n = 1.45. What angle of incidence, 
will cause the internally refracted ray to be parallel to the base of the prism?
A. 46.5 
B. 30.0
C. 20.2 
D. 5.70
E. this cannot happen
The first stars formed in the Universe were composed of 90% hydrogen, 10% helium, and very little else
a. True b. False Indicate whether the statement is true or false
Tonight the Moon is full. Therefore, in one week, the Moon will be
A) full. B) first quarter. C) third quarter. D) new.