SF026: PAST YEAR PSPM QUESTIONS
CHAPTER 3: ELECTRIC CURRENT AND DIRECT CURRENT
CIRCUIT
PSPM II 2005/2006 NO. 3
3. (a) Write Kirchhoff’s law for the conservation of energy.
FIGURE 2
(b) A circuit of two batteries and two resistors is as shown in FIGURE 2. Determine
the magnitude and direction of current in the circuit. [Ans: . ;
Anticlockwise]
[3 marks]
PSPM II 2005/2006 NO. 11(A),(B)
11. (a) Explain how to convert a galvanometer to
(i)
Voltmeter.
(ii)
Ammeter.
[2 marks]
(b) A galvanometer has an internal resistance of 25Ω and a full scale deflection of
5. Calculate
(i)
the value of the resistor used to convert the galvanometer to voltmeter
with a maximum range of 15. [Ans: ]
(ii)
the power consumed by voltmeter at full scale deflection. [Ans: . ]
[4 marks]
PSPM II 2006/2007 NO. 3
3. (a)
FIGURE 2
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SF026: PAST YEAR PSPM QUESTIONS
Based on the voltage-current graph in FIGURE 2, is the conductor ohmic or nonohmic? Justify your answer.
(b) A platinum wire has a resistance of 1.5Ω at 30. Calculate the wire resistance at
100 if the wire temperature coefficient of resistance is 3.92 10 ! . [Ans:
. ]
[4 marks]
PSPM II 2006/2007 NO. 11
11. (a) State Ohm’s law.
[1 mark]
(b)
FIGURE 7
FIGURE 7 shows the arrangement of five equal resistors in a circuit. Calculate
(i)
The equivalent resistance between point " and #. [Ans: $% &]
(ii)
The voltage across point ' and (. [Ans: )*+ )]
(iii) The voltage across point ( and #. [Ans: )+% )]
[6 marks]
(c)
FIGURE 8
The internal resistance of all the batteries in FIGURE 8 are negligible. Calculate the
current ,! , ,- and , when switch S is
(i)
Open. [Ans: . &]
(ii)
Closed. [Ans: . ; . ; . /]
[8 marks]
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SF026: PAST YEAR PSPM QUESTIONS
PSPM II 2007/2008 NO. 3
3. A light bulb has a rating of 230 and 601. Calculate the quantity of charge that
passes through the bulb in 32. [Ans: ∆4 . &5]
PSPM II 2007/2008 NO. 11
11. (a) State Kirchhoff’s laws.
[2 marks]
(b) Battery P with emf 1.3 and internal resistance 2Ω, battery Q with emf 1.5 and
internal resistance 0.8Ω, and a 4Ω resistor are connected in parallel.
(i)
Sketch the circuit diagram.
(ii)
Calculate the current in battery P, battery Q and the 4Ω resistor. [Ans:
. ; . ; . /]
(iii)
Calculate the potential difference across the 4Ω resistor. [Ans: ) . /)]
[8 marks]
(c) Given a voltmeter, a battery, a known resistor 8! and an unknown resistor 8- .
With the aid of a diagram, describe a method to determine the value of 8- .
[5 marks]
PSPM II 2008/2009 NO. 3
3.
FIGURE 1
Calculate the effective resistance of the circuit in FIGURE 1. [Ans: . ]
[4 marks]
COMPILED BY: MR PEK CHUN HOE (KML)
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SF026: PAST YEAR PSPM QUESTIONS
PSPM II 2008/2009 NO. 11
11.
FIGURE 6
FIGURE 6 shows a Wheatstone Bridge with a variable resistor P.
(a) Describe how to balance the Wheatstone Bridge.
[2 marks]
(b) Once the Wheatstone Bridge is balanced,
(i)
Explain the principles used in determining the resistance of P.
(ii)
Calculate the resistance of P. [Ans: . ]
[7 marks]
(c) (i) Explain the need to use high voltage to deliver grid electricity.
(ii) A copper transmission cable of cross sectional area 7.0::- is carrying
0.12 current. If there is an increase in temperature by 15, calculate the
power loss per unit length in the cable. [Ans: . <]
;
Given:
Resistivity of copper 1.7 10= Ω:.
Temperature coefficient resistivity of copper 3.9 10 !
[6 marks]
PSPM II 2009/2010 NO. 3
3. The dimensions of two copper wires, P and Q are given in TABLE 1.
Wire
P
Q
TABLE 1
Length
>
2>
Radius
?
?
2
Calculate the ratio of resistance of P to Q.
[Ans: &]
4
[3 marks]
COMPILED BY: MR PEK CHUN HOE (KML)
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SF026: PAST YEAR PSPM QUESTIONS
PSPM II 2009/2010 NO. 11
11. (a) An electric bulb is labeled 1001, 240. Calculate the power rating of a bulb
with twice the resistance of the 1001 bulb. [Ans: @AB ]
[3 marks]
(b)
FIGURE 5
FIGURE 5 shows a circuit with two batteries, three resistors and a switch. Using the
given labeled circuit diagram, determine the ammeter and voltmeter readings when
the switch in the circuit is
(i)
Opened. [Ans: . /; ) )]
(ii)
Closed. [Ans: . ; ) . /)]
[12 marks]
PSPM II 2010/2011 NO. 3
3. A wire of length 10: and a diameter of 4:: has an electrical conductivity of
6.0 10C Ω! :!. Calculate
(a) the resistivity of the wire. [Ans: D . / & <]
(b) the resistance of the wire. [Ans: . ]
[4 marks]
PSPM II 2010/2011 NO. 11
11. (a)
FIGURE 5
FIGURE 5 shows a circuit with unknown resistor 8 and emf E. If the currents in the
circuit are as shown, calculate the
(i)
current ,F . [Ans: &]
(ii)
Value of 8. [Ans: ]
(iii) Value of E. [Ans: G )]
[3 marks]
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SF026: PAST YEAR PSPM QUESTIONS
(b)
FIGURE 6
FIGURE 6 shows a simple potentiometer. Wire PQ has length 100(: and resistance
2.4Ω. The galvanometer G shows no deflection when the jockey is at X, a distance
60(: from P.
(i)
By neglecting the internal resistance of the 2.0 battery, calculate the emf
EH of battery B. [Ans: GI . )]
(ii)
The galvanometer and battery B are replaced by a voltmeter of internal
resistance 20Ω. Calculate the reading of the voltmeter if the jockey is
maintained at its position, X. [Ans: )J . )]
[8 marks]
(c) For a Wheatstone bridge,
(i)
Sketch and label the circuit.
(ii)
Write the resistance equation when the bridge is balanced.
(iii) State one of its application.
[4 marks]
PSPM II 2011/2012 NO. 2
2. (a) State Ohm’s law.
[1 mark]
(b) A potential difference of 15 is applied across a uniform wire of length 2.80:
and radius 0.30(:. If 0.60 current flows in the wire, calculate
(i)
the resistance of the wire. [Ans: . ]
(ii)
the resistivity of the wire. [Ans: D . <]
[3 marks]
(c)
FIGURE 2
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SF026: PAST YEAR PSPM QUESTIONS
Two batteries and four resistors are connected in a circuit where currents ,! , ,- and ,
flow as shown in FIGURE 2.
(i)
Calculate ,! , ,- and , . [Ans: −. & ; −. ; . /]
(ii)
What does it imply if the calculated current is negative?
(iii) Calculate the potential difference between points X and Y. [Ans: )J −
)L . /)]
(iv)
Calculate the total power dissipated in the circuit. [Ans: . ]
[11 marks]
PSPM II 2012/2013 NO. 2
2. (a) (i) Define the emf of a battery.
(ii) A battery has an emf of 12 and internal resistance ? is connected to a resistor
8 4Ω. The voltage across the battery terminal is measured to be 8. Calculate the
internal resistance. [Ans: M ]
[3 marks]
(b)
FIGURE 3
FIGURE 3 shows a circuit consisting of batteries with internal resistance 6, 1Ω
and 10, 2Ω and connected to resistors of 8Ω, 9Ω and 12Ω. By using the anticlockwise loop as shown, calculate
(i)
The current that flows through the 8Ω resistor. [Ans: . ]
(ii)
The potential difference between point A and C, NO . [Ans: )5 . )]
[6 marks]
(c) The heating element is made of 1.0: long wire with cross-sectional area of 3.1 10P :- . The wire has a resistivity of QR 6.8 10S Ω: at a temperature TR 320 and a temperature coefficient of resistivity U 2.0 10 V ! .
(i)
Define temperature coefficient of resistivity, U.
(ii)
Determine the resistance of the heating element at an operating
temperature of 420. [Ans: /. ]
(iii)
If the heating element is connected to 100 power supply, is the power
dissipated at 320 and 420 are the same? Justify your answer. [Ans:
WBAMXYYZ<A/\@+]Z@^A_.]
[6 marks]
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SF026: PAST YEAR PSPM QUESTIONS
PSPM II 2013/2014 NO. 2
2. (a) (i) State ONE application of a Wheatstone bridge. Explain the principle used in
such application.
(ii)
FIGURE 3
State TWO laws to be used in determining the currents in the circuit as shown in
FIGURE 3.
[5 marks]
(b) A toaster has a heating element made of nichrome wire and connected to a 220
source. The wire is initially at 20 with current 1.8. When the toaster reaches its
final operating temperature, the current is 1.53. Calculate the
(i)
power delivered to the toaster at its operating temperature. [Ans: /. /]
(ii)
final temperature of the heating element if the temperature coefficient of
resistivity for nichrome wire is 4 10` ! . [Ans: a /]
[4 marks]
(c) The emf of a battery with internal resistance is 12. When an unknown resistor 8
is connected to the battery, the current is 0.8. If another resistor 8 is added in series,
the current is 0.6. Calculate the
(i)
value of the resistor 8. [Ans: ]
(ii)
internal resistance of the battery. [Ans: M ]
(iii)
Terminal voltage of the battery. [Ans: )bAM<X@Z;*ZbbAM% /)]
[6 marks]
PSPM II 2014/2015 NO. 2
2. (a)
FIGURE 3
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SF026: PAST YEAR PSPM QUESTIONS
FIGURE 3 shows some of the free electrons inside a section of a cylindrical copper
wire. The wire is connected to an emf source, and the direction of the electric field, c
is as indicated in the figure.
(i)
Sketch a diagram to show the motions of one free electron, the directions
of drift velocity and the current.
(ii)
If the current in the wire is 50:, calculate the number of electrons
passing a point in 102. [Ans: @ & ]
[5 marks]
(b) A battery has an emf of 9. The terminal voltage is 8 when the battery is
connected across a resistor of 5Ω. Calculate the
(i)
current through the resistor. [Ans: . /]
(ii)
power dissipated by the resistor. [Ans: . &]
(iii)
Internal resistance of the battery. [Ans: M . /]
[3 marks]
(c)
FIGURE 4
By referring to FIGURE 4, determine
(i)
,! , ,- and , . [Ans: . ; . ; . /]
(ii)
The potential difference across the 18Ω resistor. [Ans: )& )]
[7 marks]
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