Queries on Motors and Generator Questions from SuccessOne (1 Viewer)

[Nasti]

i was doing some of the multiple choice questions from successone book, the ones at the beginning which are sectioned off under their topics (beginning page 26)

i looked at the answers, referred to my contexts and excel book and the explanation of the answers and it still makes no sense

so, if you have this book and can provide me with a more professional/theotrical and detailed explanations of the following questions, PLEASE do so

Multiple Choice Question 1 p.26
Multiple Choice Question 5 p.28
Multiple Choice Question 6 p.29
Multiple Choice Question 11 p.30
Multiple Choice Question 14 p.32

if the explanations were decent then i wouldnt be here asking but i honestly think they are crap

if need be, i will post scans of the questions, answers and explanations, but i think it's a fair guess that the majority of the people here have the successone book

thanks in advance for your help

 

[BlackJack]

My one's from last year, so it could be different. But:

Q1 p.26: faraday's expt:

A, the wire rotates clockwise because we can apply the hand rule to determine the direction of the force. This is because the wire is NOT parallel to the magnetic field (up and curving out). The current is down, and sloping away from the magnet as well.

Q5. beta particle in B field.
D, but the wording is very sus. Note that the parallel component of the electron is not affect by the magnetic field, thus resulting in the electron spiralling to the right. Hence it cannot move in a circular path
(implying deceleration of the parallel). Looking in the net direction of the electron it is clockwise.

Q6:
D. This is because once we do build up the charge at the ends there is no more build up of emf as the magnetic field one is cancelled by the charge imbalance. Hence no more slow down from induction (if you like, it can be thought of from the conservation of energy, as no more energy is put into displacing the electrons there's no where else the KE of the rod can go...).
Note this is different from magnetic braking.

Q11:
A, the only reason I can garner is that you need an extra amount of energy to overcome the inertia of the (stationary) elevator which is not required while the elevator is in motion. Back emf applies at high rotor speeds and is not concerned in the initial situation.

Q14:
Initial conditions implies RS -> PQ as RS moves down in magnetic field going left, and the generator is sinusoidal (consider components perpendicular to magnetic field)