# Question：What is the difference between flux and current?

• LeeGru
In summary, the conversation discusses the difference between flux and current for neutrons and how to calculate them. Flux is a scalar value while current is a vector with direction. The question also touches on the ratio between total neutron current and flux and how to calculate it in MCNP.

#### LeeGru

TL;DR Summary
calculate the flux and current of neutron by MCNP
Guys,I need to calculate the flux and current of neutron by MCNP.So what's the difference between them ,and How to calculate them?
Any ideas?

Flux is a flow/area/time, so in the case of neutrons it would have units like neutrons/(cm^2 - sec). Current is a flow/time, so it would have units like neutrons/second. So the current will be the flux integrated over some surface. How you calculate theme depends on the problem given.

• LeeGru
LeeGru said:
Guys, I need to calculate the flux and current of neutron by MCNP.So what's the difference between them ,and How to calculate them?
Flux is a scalar value, while current is a vector, which has a direction.

Is the question about neutron current (or particle current) or current density?

• LeeGru
Astronuc said:
Flux is a scalar value, while current is a vector, which has a direction.

Is the question about neutron current (or particle current) or current density?
I need to calculate the ratio between the total neutron current and the total neutron flux.How could obtain this value?

phyzguy said:
Flux is a flow/area/time, so in the case of neutrons it would have units like neutrons/(cm^2 - sec). Current is a flow/time, so it would have units like neutrons/second. So the current will be the flux integrated over some surface. How you calculate theme depends on the problem given.
Thank you very much.I need to calculate the ratio between the total neutron current and the total neutron flux.How could I obtain this value in MCNP

## Question 1: What is flux?

Flux refers to the flow of a physical quantity through a surface. It can be thought of as the amount of "stuff" passing through a given area.

## Question 2: What is current?

Current refers to the flow of electric charge through a conductor. It is typically measured in amperes (A).

## Question 3: What is the relationship between flux and current?

The relationship between flux and current is that current is the rate of change of flux. In other words, the amount of current flowing through a surface is directly proportional to the amount of flux passing through that surface.

## Question 4: How are flux and current different?

The main difference between flux and current is that flux is a general term that can refer to the flow of any physical quantity, while current specifically refers to the flow of electric charge.

## Question 5: Can flux and current be present without each other?

Yes, it is possible for flux and current to exist without each other. Flux can be present without current if there is a change in the amount of a physical quantity passing through a surface, but no flow of electric charge. Similarly, current can be present without flux if there is a flow of electric charge through a conductor, but no change in the amount of a physical quantity passing through a surface.