Dual Nature Of Matter

Question 1

Indeed, the rest mass of a photon is zero. However, photons still have momentum despite having zero rest mass. Why?

Answer 1

This is because their energy and momentum are related to their frequency and wavelength.
P = hv/c = h/λ

Question 2

Role of Moderator? Impact on the rate of rxn?

Answer 2

Moderators in nuclear reactors slow down neutrons produced during fission, increasing the likelihood of further fission reactions and maintaining a sustained and controlled chain reaction.
Increases the rate of rxn.

Question 3

How do Moderators increase the likelihood of rxn?

Answer 3

Moderators increase the likelihood of further fission reactions by slowing down fast neutrons to thermal (slower) speeds, which are more likely to be captured by fissile nuclei, like uranium-235.

Question 4

Role of Control Rods? Impact on rate of rxn?

Answer 4

Control rods in nuclear reactors absorb neutrons, reducing the number of neutrons available for fission, thereby controlling or stopping the chain reaction to manage the reactor’s power output and ensure safety.
Decreases the rate of rxn

Question 5

What is a Multiplication Factor ‘K’?

Answer 5

Rate of neutrons produce / Rate of neutrons absorbed

Question 6

If K>1
K<1
K=1

Answer 6

Uncontrolled
Controlled
Critical Point

Question 7

Energy produced per rxn in Nuclear Fission?

Answer 7

200MeV

Question 8

The velocity of light in vacuum can be changed by changing _____________?

Answer 8

In vacuum the velocity of light is always CONSTANT i.e 3 × 10^8 m/s