# electrical fundementals review questions help

Discussion in 'Homework Help' started by kaytoi, Dec 4, 2010.

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1. ### kaytoi Thread Starter New Member

Nov 7, 2010
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Hey guys, my brain has hit full saturation point! I have completed my review questions which consist of 90 questions. Im finished but im unsure of the answer i have given to the questions below. Any help / education would be greatly appreciated!

1)A Potentiometer is a variable resister which:
A) Has 3 terminals connected in series with the load?
B) Has 2 terminals connected in series with the load?
My answer: I know how it looks like in a circuit but i think the top point of the POT + the winper arm make the pot in series with the load, thus making the answer B?

2) In electrolytic capacitors does the electrolyte as the
A) negative plate?
B) dielectric?
My Answer: I think its Negative plate, very hard to research this answer!!

3) A ceramic capactir is so named because of the use of the ceramic
A) Casings
B) dielectrics
My Answer: B - The dielectic between the plates is made of a ceramic.. tho in notes i have read that its because of the casing? ....

4) A capactor in series with a resister in a DC circuit:
A) current flow slightly reduced
B) no current flows
C) the circuit is in resonance
My answer: B.. im confused here, for me i picture the resister slowing down the charge cycle of a capacitor, once the capacitor has done its 5 TC's its charged and no more current flows in the circuit? I'm unsure, thats thats my reasoning...

5) Magneto-motive force ub a magnetic circuit is analagous to:
A) Current flow DC
B) Resistance in DC
C) voltage in DC
My answer: I have no idea i cant find anything like this in any of my books or notes, im completely baffled here!

6) If a switch is closed in a circuit and connects a coil of wire to a DC course voltage the current does not immediatly establish itself at its max value.. the delayed build up of current is due to:
A) mutual inductance
B) self inductance
C) impedence of circuit.
My answer: Self inductance, i realise how inductors work and the flow in a coil of different polarities so answer is B.

7) for a conductor to have a voltage induced into it there must be a
A) potential differene between the ends of the conductor.
B) no relative motion between conductor and the flux
C) change in megnetic flux
My ansewer: A " a potential diff is an electomotive force generated by the cutting acros the flux" "How ever a conductor cannot store electric charge... so voltage is present only while the motor of flux cutting across the conductor is producing the induced voltage" But im confused... so a motion has to still happen ?

8) When a inductor and lamp are connected in series wit ha DC supply the lamp shines bright. If an iron core is now inserted into the inductor the lamp brightness will?
A) diminish
B) increase
C) be unaffected
My answer: a core will increase inductance, when put in the bulb would diminish?

9) The variac is an auto-transformer with a variable tap for the?
A) Primary
B) secondary
C) primary and secondary
My answer: http://en.wikipedia.org/wiki/Autotransformer im looking at it and reading... i think i my brain is fried... confirming my answer is C. Both primary and secondary winding are used.

10) The coil of a moving coil instrument moves to its deflected position without oscillation, This dead beat movement is secured by:
A) Having phosphor bronze torque springs wounder in opposite directions
B) The Large mass of the coil and point movement
C) the damping effeft of eddy currents blowing in the coil former.
My answer: i put in A, control springs. I cant find anything in my notes to tell me how on earth the dampening happens!!!!! driving me crazy! and Q11 confuses me more with this one..

11) The coil of a moving coil meter is wound on a thin aluminum former this is done to:
A) increase strength of coil assembly
B) provide correct tamp compensation
C) provide eddy current damping of the meter movement.
My answer: Not knowing Q10 makes this hard... i dont think its to increase strength because there way more things stronger out there... temp compensation aluminium? dont think so... C looks logical to me? need more info.

Anything to do with calculations i have no problems its just these few odd questions that have me stumped!

Thank you.

Apr 5, 2008
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kaytoi likes this.
3. ### kaytoi Thread Starter New Member

Nov 7, 2010
2
0
thank you, got all my answers, can i have this thread deleted, thanks