You are Here: Home >< Physics

# Pair production

Announcements Posted on
Would YOU be put off a uni with a high crime rate? First 50 to have their say get a £5 Amazon voucher! 27-10-2016
1. In pair production, why the particles produced curved away from each other in opposite direction in magnetic field?
2. During pair production, momentum must be conserved as there are no external forces acting on it. Both linear and angular momentum must be conserved so they "curve" away from each other in order to conserve momentum.
3. (Original post by alesha98)
In pair production, why the particles produced curved away from each other in opposite direction in magnetic field?
Charge must be conserved. In pair production, you initially have no charge (as no particles). Therefore the two particles produced (e.g. an electron and a positron) must have opposite and equal charges.

In a bubble chamber, or something similar, which is what produces those photos of the particle tracks, a magnetic field is applied. Charged particles curve in magnetic fields as the magnetic field provides a centripetal force on the particles. This force acts in opposite directions for oppositely charged particles, hence the two particles produced curve in opposite directions.
4. (Original post by NeverLucky)
During pair production, momentum must be conserved as there are no external forces acting on it. Both linear and angular momentum must be conserved so they "curve" away from each other in order to conserve momentum.

Of course angular momentum is conserved, but that's not why they follow curved paths.

They curve away because they are charges moving in a magnetic field.
5. (Original post by alesha98)
In pair production, why the particles produced curved away from each other in opposite direction in magnetic field?
In particle physics experiments, there is usually a magnetic field present. If the particles are charged, the antiparticle has opposite charge, and so they move in opposite directions. They curve because the force acts perpendicular to the motion of the particle.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: August 5, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

Find out here

### How to cope with a heavy workload

Poll
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.