Nuclear physics questions + MCQ

[darkpichu]

Thanks folks for giving me explanations for these questions!

 

[destined007]

Q27) A is correct
the close end of the tube is node and open end is anti-node. At nodes the intensity is minimum and at anti-nodes the intensity is maximum. The longer the arrows the higher the intensity.

Q32) A is correct
Q=It
Q=8 x 10^-3 x 0.02 = 1.6 x 10^-4 C = 0.16 x 10^-3 C= 0.16 mC

Q33) C is correct
V1=5/(5+5) x 2 = 1 V
V2=3/(3+2) x 2= 1.2 V

V1-V2= 1-1.2 = -0.2 V

Q20) B is correct
Just imagine the diagram when the weight is applied. The part Y and X will stretch (move outward), so there is tension. The part Z will move inward, so there is compression.

Q7) C is correct
from vector diagram is can be determined that:
v=u + x

compare the above expression with v=u+at
thus, x = at

 

[destined007]

Also tell what question paper the question is from next time.
Q7)a)
i) Energy required to "completely" separate the nucleons in a nucleus. (remember it)
ii) at the peak. The more stable the element the more it will be close to peak. Iron is the most stable (so is at the peak) and every other element tries to achieve stability of Iron.

b)i)(235 +1) - (142 + 90)= 4 neutrons
ii) 1) E= (8.37 × 142 + 8.72 × 90) – (235 × 7.59) (7.59, 8.37 and 8.72 are energy 'per nucleon'. So you will multiply it with total number of nucleons to get the total energy)
= 1973.3 – 1783.7
= 189.6 MeV

2) E=mc^2
m=E/c^2 = (189.6 x 1.6 x 10^-19 x 10^6)/(3 x 10^8)^2 (convert energy into Joules by x 1.6 x 10^-19 x 10^6 ) (1 eV= 1.6 x 10^-19 J)
m=3.37 x 10^-28 kg

 

[darkpichu]

Thanks destined but for the nuclear question part b)i) why did you subtract (235 × 7.59)?

 

[destined007]

We are to calculate energy 'defect' (energy release). Before and after the reaction the total masses are different and the lost mass is converted into energy. So we subtract the value to get the difference.