Search found 11 matches

by r.jenkins
Sat Sep 18, 2010 5:31 pm
Forum: High School Physics
Topic: Neutron stars/pulsars and black holes on HR diagram
Replies: 1
Views: 9705

Neutron stars/pulsars and black holes on HR diagram

Hi,

As high mass stars approach their death to become neutron stars, black holes etc, what direction on the HR diagram do they head and where do they end up resting (relative to the HR diagram because they are obviously not on it anymore)?

Thanks
by r.jenkins
Thu Sep 09, 2010 8:51 pm
Forum: High School Physics
Topic: open and globular clusters
Replies: 1
Views: 9182

open and globular clusters

Hi,
If open clusters are considered younger than globular clusters, do open clusters eventually form to become globular clusters? If not, what is the life cycle of open clusters?

Thanks
by r.jenkins
Mon Sep 06, 2010 8:29 pm
Forum: High School Physics
Topic: astrophysics - CNO cycle
Replies: 1
Views: 9238

astrophysics - CNO cycle

Hi, The CNO cycle to fuse hydrogen to helium only occurs at over 1.6x10^7 K. At this stage the only fusion product is helium... so where is the carbon, nitrogen and oxygen coming from? Also, some texts call C, N and O all catalysts, while others say that only C is a catalyst! I seem to think the lat...
by r.jenkins
Mon Aug 30, 2010 7:40 pm
Forum: High School Physics
Topic: astrophysics question
Replies: 1
Views: 8964

astrophysics question

Hi, just in addition to the previous question... Q: The ratio of radii of orbits of two stars in a binary is about 3:5. Use this to estimate the massess of each star. A: Since the ratio of diameters of orbits is 3:5, then ratio of their masses is 5/8 and 3/8. These masses are therefore 5.25x10^30kg ...
by r.jenkins
Mon Aug 30, 2010 7:23 pm
Forum: High School Physics
Topic: astrophysics: binary stars and stellar masses
Replies: 0
Views: 9634

astrophysics: binary stars and stellar masses

Hi, When studying visual binary stars, we use the formula M=(4pi^2R^3)/(GT^2) where T is defined as the period of the "system", with the 2+ stars orbiting a centre point in space. What exactly is this period? What does it look like? How are the stars moving? I've only ever encounted "...
by r.jenkins
Wed Jul 07, 2010 12:40 pm
Forum: High School Physics
Topic: Time dilation
Replies: 2
Views: 9761

Time dilation

Hi, With twins paradox they say that the person flying at relativistic speeds away from Earth will 'age less' - understandable! But why then, if this person was to watch an event happening on earth, does it appear to go slower then it would in their 'spacecraft'? Don't these contradict each other? T...
by r.jenkins
Fri Jun 18, 2010 5:46 pm
Forum: High School Physics
Topic: superconductors and internal magnetic field
Replies: 1
Views: 9181

superconductors and internal magnetic field

Hi, just want to check this: When we say that the movement of a magnet onto a superconductor induces currents in the superconductor which create a magnetic field opposing the magnetic field of the magnet, is it correct to say that the induced currents where solely the product of originally moving th...
by r.jenkins
Thu May 20, 2010 9:51 pm
Forum: High School Physics
Topic: p-type semiconductors
Replies: 3
Views: 9932

p-type semiconductors

Hi,
I understand with n-type semiconductors how there is a free unbonded electron introduced by the group 5 dopant which can easily move under an applied voltage, but with p-type I can't see any reason why electrons (and positive holes) would want to move?

Thanks
by r.jenkins
Tue May 11, 2010 10:18 pm
Forum: High School Physics
Topic: Hertz's experiment receiver
Replies: 3
Views: 10369

Re: Hertz's experiment receiver

Maybe I put it the wrong way! Hertz discovered that the major factor (but not the only factor) causing the sparking was the photoelectric effect caused by the UV emission of the inducation coil and transmitting loop. When he blocked this UV there was still a small spark occuring in the receiver loop...
by r.jenkins
Fri May 07, 2010 6:09 pm
Forum: High School Physics
Topic: Hertz's experiment receiver
Replies: 3
Views: 10369

Hertz's experiment receiver

Hi,
In Hertz's original experiment to verify Maxwell's prediction of electromagnetic waves, what is actually 'happening' with the receiver? What is causing it to spark also?

Thanks
by r.jenkins
Sat May 01, 2010 10:50 pm
Forum: High School Physics
Topic: force on a charge in magnetic field
Replies: 1
Views: 9235

force on a charge in magnetic field

Hi, It is said that for a force to be experienced on a charged particle in a magnetic field, the particle must have a velocity: ie by the formula: F = qvBsin@. Why is it that the particle has to have a velocity? In the similar scenario of a electric field, the formula F=qE, the charged particle expe...

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