Current, force, weight.
What am I over looking on this question? The answer on the mark scheme is 'A' but how can you get a negative reading?
You can get a negative reading because the balance was zeroed after something was put on it.
Original post by ashboot
Knew it would be something stupid I was over looking -.-
Thank you.
Thank you.
Haha, no problem, physics always has those little annoying things about it!
The important point in this question is about the force on the wire due to the current in it passing through the magnetic field of the magnets.
F=BLI
and as B and L don't change, it's the change in the current that causes this change in the force.
If you reverse the current you reverse the force.
If you double the current you double the force.
That's why, if you reverse and double the current, you get a force twice as large in the opposite direction, giving a double negative reading.
The positive reading would be the case where the force (of the wire) on the scale pushes downwards, and the negative reading implies the force on the scale is pushing upwards.
F=BLI
and as B and L don't change, it's the change in the current that causes this change in the force.
If you reverse the current you reverse the force.
If you double the current you double the force.
That's why, if you reverse and double the current, you get a force twice as large in the opposite direction, giving a double negative reading.
The positive reading would be the case where the force (of the wire) on the scale pushes downwards, and the negative reading implies the force on the scale is pushing upwards.
Quick Reply
Related discussions
- don't understand force exerted by A on B
- Which Fleming's Hand Rule to Use?
- Physics question- man in lift
- A level maths mechanics moments and forces question
- Why is tension not equal to weight in moments questions?
- Tips to lose weight. Only serious responses please.
- Physics question moments
- Further Mechanics 1 Question
- Physics question acceleration
- Banked Tracks For Turning
- Force Diagram (A2 Edexcel)
- economics - macro
- Vectors with mechanics question
- Mechanics help
- AQA GCSE Physics Paper 2 (Higher Tier) 8463/2H - 23 Jun 2022 [Exam Chat]
- Physics question circular motion
- Physics help
- A level physics
- Tension in a Simple Pendulum
- Physics question HELP !!
