You are Here: Home

# Physics challenge watch

Announcements
1. Yeah, regarding my post about a "spinning magnetic disc" in the first question of the exam, sorry, it should be "spinning *metal* disc", as it does not matter whether or not it is magnetic. (Thanks Rob)
2. The answer to the question is actually 0.0157Volts and can be easier calculated using V=ð*r^2*B*f, where V is the induced voltage required, B is the magnetic flux density r is the radius of rotating disk and f is the frequence of oscillations. Substituting...
V=ð*(0.1)^2*0.01*50=0.0157Volts approximately=0.016(2 d.c).
I think this way is much easier.
Btw did you find 0.0157 or 0.016 exactly?
3. Well Done. Thank you.
I found 0.0157 but I rounded it off.
You are right that you can do it both ways, whichever is easier is personal choice I guess..... I just like the neat way that it relates to the rate of change of flux, but is subtly different.

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:
Updated: June 21, 2003
Today on TSR

### Should I drop out of uni

...to become a pro gamer?

### University open days

• Sheffield Hallam University
Thu, 13 Dec '18
• University of Buckingham
Thu, 13 Dec '18
• University of Lincoln
Mini Open Day at the Brayford Campus Undergraduate
Wed, 19 Dec '18
Poll
Useful 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