You are Here: Home >< Physics

# Electric Field Strength Watch

1. Question taken from:

https://isaacphysics.org/questions/c...lls_book_ch_h2

Two charges are stuck to a metre stick: a +1.0pC charge at the 0cm mark,
and a −1.0pC charge at the 10cm mark.
What is the strength of the electric field at the 20cm mark?

Am I correct in assuming that 20cm mark the field strength is due only to the -1pC point charge giving a value of 0.9N/C ( i.e. 9x10^9x1x10^-12/0.01^2)?
The application on the web page refuses to accept that as the right value.
2. (Original post by xlaser31)
Question taken from:

https://isaacphysics.org/questions/c...lls_book_ch_h2

Two charges are stuck to a metre stick: a +1.0pC charge at the 0cm mark,
and a −1.0pC charge at the 10cm mark.
What is the strength of the electric field at the 20cm mark?

Am I correct in assuming that 20cm mark the field strength is due only to the -1pC point charge giving a value of 0.9N/C ( i.e. 9x10^9x1x10^-12/0.01^2)?
The application on the web page refuses to accept that as the right value.
Work out the field strength at 20cm due to each charge in turn and then add together...
the fancy name for this is superposition
3. (Original post by xlaser31)
Question taken from:

https://isaacphysics.org/questions/c...lls_book_ch_h2

Two charges are stuck to a metre stick: a +1.0pC charge at the 0cm mark,
and a −1.0pC charge at the 10cm mark.
What is the strength of the electric field at the 20cm mark?

Am I correct in assuming that 20cm mark the field strength is due only to the -1pC point charge giving a value of 0.9N/C ( i.e. 9x10^9x1x10^-12/0.01^2)?
The application on the web page refuses to accept that as the right value.
Both charges will have effect on the field strength at 20 cm. -1.0pC will cause attraction and +1.0pC will cause repulsion if there is a positive point charge at 20 cm. To add on, your conversion from cm to m is incorrect.
4. I hope i am right
Attached Images

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: November 14, 2016
Today on TSR

### Students dropping out of Oxbridge

Why are there so many?

### Will my dog think I’m dead when I’m at uni?

Poll

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.