d) half the potential difference of the 1-pF capacitor e) none of the above 28.
ID: 1409543 • Letter: D
Question
d) half the potential difference of the 1-pF capacitor e) none of the above 28. A car battery is rated at 80 A.hr. An ampere-hour is a unit of. a) power b) energy c) current d)charge 29. The units of resistivity are: a) ohm b) ohm -meter c) ohm/meter d) ohm/meter 30. Energy may be measured in: a) kilowattb) joule-second c)watt d) joule-second e) kilowatt-hour 31.Four 20-Ohm resistors are connected in parallel and the combination is connected to a 20-V emf device. The current in any one of the resistors is: a) 0.25 A b) 1.0A c) 4.0A d)5.0 A e) 100 A 32. Four 20-Ohm resistors are connected in series and the combination is connected to a 20-V emf device. The current in any one of the resistors is: A) 0.25 A B)1.0 A C)4.0A D)5.0A E) 100 A 33·The resistance of a conductor does not depend on its a) mass b) length c) cross-sectional aread) resistivity 34. The temperature of a copper wire is raised. Its resistance a) decreases b) remains the same c) increases d) any of the above, depending on the temperature involved 35. An electric heater draws a current of 20A when connected to a 120 V power source. ItsExplanation / Answer
(28) ans
ampere* hour is unit of charge
explation : ampere is unit of current
hour is unit of time
therefore the charge =current*time=ampere*hour
the correct option is D
(29) ans
the unit of resistivity is ohm-meter
the correct option is B
(30) ans
the energy can be measured is kilowatt-hours
this unit can be measured basing on joules law
the correct option is E
(31) ans
R1=R2=R3=R4=20
the four resistance is connected in parallel connection
the effective resistance R=R1R2R3R4/(R1R2R3+R2R3R4+R3R4R1+R4R1R2)
=R/4
=20/4=5 0HMS
the potential difference V=20V
the current I=V/R=20/5=4 A
the current in one resistance I=[R1/R1+R2+R3+R4]I
=[20/80]4=1A
the correct option is B
(32) ans
the resistance R1=R2=R3=R4=20 ohms
the four resistance are connected in series
R=R1+R2+R3+R4=20+20+20+20=80 ohms
the potential difference v=20 v
the current in the circuit=v/R=20/80=0.25A
in series connection is the current is same for any resistance
the correct option is A
(33) ans
the resistance of conuctor is does not depends on area -crossection of body
the corrct option is c
(34) ans
the temperature of copper is raised the resistance is also increases
because the resistance is directly propertional to temperature
so the correct option is C
(35) ans
the current i=20A
potential difference V=120
this concept belongs to ohms law
v=iR
120=20 R
the resistance R=120/20=6 ohms
the resistance of the conductor=6 ohms
(43) ans
the current passing in two parallel wire is repel eachother
because the connections are same for both sides
so like connection are repel eachother
the correct option is B
(44) ans
the current loop in a magnetic field B does not tends to rotate
because the current in plane of loop is perpendicular to magneticfield
because for current loop if the curling of the fingers of the right hand show the direction of current in the loop,the extented thumb will give us the direction of magneticfield along its axis of the current loop
the correct option is B
45 ans
the magnetic force is acting on the wire
towards the right of the page
because the lorentz force the magnetic force is perpendicular to the current direction
so current lies the bottom of page the magnetic force lies the right of page
the correct option is D
46 ans
the magnetic field the direction is moves towards your left
basing on lorentz force
the correct option is D
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