Semestertoets test 2

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Semestertoets / test 2
1. Die figuur toon n lang, nie-geleidende
massalose staaf met lengte L wat roteer om sy
middel en gebalanseer word deur n gewig W op n
afstand x vanaf die linkerkant. Aan die linker
en regterkante is klein geleidende sfere met
ladings van q en 2q vas. n Afstand h onder
elkeen is vaste sfere met ladings Q. Bereken die
afstand x wanneer die staaf horisontaal en
gebalanseer is. The figure shows a long,
nonconducting, massless rod of length L, pivoted
at its center and balanced with a weight W at a
distance x form the left. At the left and right
ends of the rod are attached small conducting
spheres with charges q and 2q. A distance h
directly beneath each is a fixed sphere with
charge Q. Find the distance x when the rod is
horizontal and balanced. (6)
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Vir watter waarde van h sal daar geen netto
vertikale krag wees as die staaf horisontaal
gebalanseer is? For what value of h will there be
no vertical force when the rod is horizontally
balanced? (3)
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2. 'n Voorwerp wat op die Aarde se ewenaar lê
word na die midelpunt van die Aarde versnel omdat
dit roteer. Bepaal hierdie versnelling as
veelvoude van g (9.8 m/s2). An object lying on
the Earth's equator is accelerated towards the
centre of the Earth because it rotates.
Determine this acceleration as multiples of g
(9.8 m/s2) (3)
Die voorwerp word na die Son versnel omdat die
Aarde in 'n amper sirkelvormige baan om die Son
roteer. Bepaal hierdie versnelling as veelvoude
van g (9.8 m/s2). This object is accelerated
towards the Sun because the Earth revolves around
the Sun in an almost circular orbit. Determine
this acceleration as multiples of g (9.8 m/s2)
(3)
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3. 'n Positiewe punt lading met 'n grootte van
4.00 ? 10-8 C word in 'n reghoekige koördinaat
sisteem by 'n punt x 0.10 m, y 0 geplaas.
'n Identiese punt lading word by 'n punt x
-0.10 m, y 0 geplaas. Bepaal die grootte en
rigting van die elektriese veld by die
oorsprong. In a rectangular coordinate system a
positive point charge with a magnitude of 4.00 ?
10-8 C is placed at a point x 0.10 m, y 0.
An identical point charge is placed at x -0.1
m, y 0. Calculate the magnitude and direction
of the electric field at the origin. (4)
Bepaal die grootte en rigting van die elektriese
veld by die punt x 0.20 m, y 0. Calculate the
magnitude and direction of the electric field at
the point x 0.20 m, y 0. (3)
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Bepaal die grootte en rigting van die elektriese
veld by die punt x 0.10 m, y 0.15
m. Calculate the magnitude and direction of the
electric field at the point x 0.10 m, y 0.15
m. (9)
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4. Veronderstel n positiewe lading is univorm
versprei oor n baie lang silindriese volume met
radius R en lading per eenheids volume van ?.
Lei n uitdrukking af vir die elektriese veld
binne die volume op n afstand r vanaf die as van
die silinder in terme van die ladings digtheid
?. Suppose positive charge is uniformly
distributed throughout a very long cylindrical
volume with radius R with charge per unit volume
?. Derive the expression for the electric field
inside the volume at a distance r from the axis
of the cylinder in terms of the charge density
?. (4)
Wat is die elektriese veld by n punt buite die
volume in terme van die lading per eenheids
lengte ? in die silinder? What is the electric
field at a point outside the volume in terms of
the charge per unit length ? in the cylinder?
(3)
Verkry die verband tussen ? en ? deur van die
antwoorde hierbo gebruik te maak. Derive the
relationship between ? and ? by using the
answers above. (3)
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6. As die battery n potensiaal verskil van 20 V
het, bepaal die ekwivalente kapasitansie van al
die kapasitore. If the battery has a potential
difference of 20 V, determine the equivalent
capacitance of all the capacitors. (5)
Bepaal die lading wat gestoor word op die
ekwivalente kapasitor. Determine the charge
stored on the equivalent capacitor. (2)
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Bereken die potensiaal verskil oor en die lading
gestoor op kapasitor C1. Give the potential
across and the charge on capacitor C1. (3)
Bereken die potensiaal verskil oor en die lading
gestoor op kapasitor C2. Give the potential
across and the charge on capacitor C2. (3)
Bereken die potensiaal verskil oor en die lading
gestoor op kapasitor C3. Give the potential
across and the charge on capacitor C3. (3)
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7. Ingenieurs benodig n kraglyn met n
weeerstand per eenheids lengte van 50 m?/km.
Watter diameter draad word benodig, as die lyn
van Koper gemaak is? Engineers call for a power
line with a resistance per unit length of
50 m?/km. What wire diameter is required if the
line is made of copper? (4)
Watter diameter draad word benodig, as die lyn
van aluminium gemaak is? What wire diameter is
required if the line is made of aluminium?
(2)
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As die koste van koper en aluminium R1.53/kg en
R1.34/kg is, watter materiaal is meer ekonomies?
(?Cu  8.9 g.cm-3, ?Al  2.7 g.cm-3) If the costs
of copper and aluminium are R1.53/kg and
R1.34/kg, which material is more economical? (?Cu
 8.9 g.cm-3, ?Al  2.7 g.cm-3) (5)
8. 'n 1250 W stralings verwarmer is gekonstrueer
om teen 115 V te werk. Wat is die stroom in die
verwarmer? A 1250 W radiant heater is constructed
to operate at 115 V. What is the current in the
heater? (2)
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Wat is die weerstand in die verhittings
element? What is the resistance in the heating
coil? (2)
Hoeveel termiese energie word in 1 uur deur die
verwarmer opgewek? How much thermal energy is
generated in 1 hour by the heater? (2)
9. Twee weerstande en twee ongelaaide kapasitore
is soos in die skets gekoppel. Wat is die
potensiaal by punt a met die skakelaar S oop
(laat V0 by die negatiewe terminaal van die
bron)? Two resistors and two uncharged capacitors
are connected as in the figure. What is the
potential at point a with the switch S open (let
V0 at the negative terminal of the
source)? (3)
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Wat is die potensiaal by punt b met die skakelaar
S oop? What is the potential at point b with the
switch S open? (3)
Wat sal die potensiaal by punt b wees as die
skakelaar S gesluit word? What will the potential
at point b be when the switch S is
closed? (1)
Hoeveel lading vloei deur die die skakelaar S na
dit gesluit is? How much charge flows through the
switch S after it is closed? (4)
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10 Bereken die strome I1, I2 en I3 in die
stroombaan. Calculate the currents I1, I2 and I3
in the circuit. (9)