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physics questions, EMF urgent help need

im having a lot of difficulty with this question, could anyone help? cheers!

:biggrin:



HRW6 28-38P When the lights of an automobile are switched on, an ammeter in series with them reads 14.0 A and a voltmeter connected across them reads 14.4 V. See Fig. 28-39. When the electric starting motor is turned on, the ammeter reading drops to 6.11 A and the lights dim somewhat.




If the internal resistance of the battery is 0.0500 and that of the ammeter is negligible, what are

(a) the emf of the battery







here is a link to the picture.


http://www.webassign.net/hrw/hrw7_27-48.gif
fabregassed
im having a lot of difficulty with this question, could anyone help? cheers!

:biggrin:



HRW6 28-38P When the lights of an automobile are switched on, an ammeter in series with them reads 14.0 A and a voltmeter connected across them reads 14.4 V. See Fig. 28-39. When the electric starting motor is turned on, the ammeter reading drops to 6.11 A and the lights dim somewhat.




If the internal resistance of the battery is 0.0500 and that of the ammeter is negligible, what are

(a) the emf of the battery







here is a link to the picture.


http://www.webassign.net/hrw/hrw7_27-48.gif


Well,the question seems confusing,though.I've tried it but i'm not much sure.
V=14.4V when connected with bulb.
I=14A
R=?
V=IR
or, 14.4=14 X R
R=1.02 ohm
E=IR + Ir
= 14(1.02 + 0.05)
=15.1 V Ans.
Reply 2
Avatar for fabregassed
fabregassed
OP
10
TymfAfterDeath
Well,the question seems confusing,though.I've tried it but i'm not much sure.
V=14.4V when connected with bulb.
I=14A
R=?
V=IR
or, 14.4=14 X R
R=1.02 ohm
E=IR + Ir
= 14(1.02 + 0.05)
=15.1 V Ans.



thanks! its right :yep:
My pleasure.
Reply 4
Avatar for djk326
djk326
I had this same problem. I realize it's almost a year later, but does anyone know how to find the current through the starting motor?

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