Q. (a) The diagram shows the voltage-current graphs for three different electrical components. Which one of the components A, B or C could be a 3 volt filament lamp? Explain the reason for your choice................... (b) Using the correct symbols draw a circuit diagram to show how a battery, ammeter and voltmeter can be used to find the resistance of the wire shown. (c) When correctly connected to a 9 volt battery the wire has a current of 0.30 amperes flowing through it. (i) Give the equation that links current, resistance and voltage.... () (ii) Calculate the resistance of the wire. Show clearly how you work out your answer and give the unit....... Resistance =... Page
(iii) When the wire is heated, the current goes down to 0.26 amperes. State how the resistance of the wire has changed....... () (Total marks) Q2. A circuit was set up as shown in the diagram. (a) The table gives the current through three of the ammeters. Complete the table to show the current through the other two ammeters. Ammeter Reading on ammeter in amps A l 0.2 A 2 0.6 A 3 0.3 A 4 A 5 (2) Page 2
(b) The reading on the voltmeter is 2 V. What is the resistance of R 2? Show your working and include the correct unit............. Resistance =... (c) In the circuit above, the resistor R 2 burned out and current stopped flowing in it. There was no other change to the circuit. Complete the table below to show the readings on the ammeters after this took place. Ammeter Reading on ammeter in amps A l 0.2 A 2 0.0 A 3 A 4 A 5 (Total 8 marks) Page 3
Q3. The diagram shows a 2 volt lighting system. Each lamp has a power of 32 watts. (i) Write down the equation that links current, potential difference and power.... () (ii) Calculate the input current to the lighting system. Show clearly how you work out your answer............. current =... A (2) (Total 3 marks) Page 4
Q4. The diagram below shows how one type of fuel gauge in a car works. A sliding contact makes contact with a resistance wire wound in a coil (rheostat). It is connected to a float via a pivot P. When the petrol level changes the circuit resistance changes. This causes the pointer in the fuel gauge to move and show how much petrol is in the petrol tank. The circuit diagram is shown below. The petrol gauge is an ammeter. Explain why the reading on the ammeter falls as the petrol is used...................... (Total 3 marks) Page 5
M. (a) C award mark if A and B identified as not filament lamp resistance increases negated by wrong statement e.g. current goes down as the lamp gets hot accept as current (through lamp) or voltage (across lamp) increases do not accept non-ohmic reason independent of choice of component (b) ammeter wire and battery only in series non standard symbols acceptable if correctly identified (labelled) for ammeter, voltmeter and battery voltmeter only in parallel with wire or battery all in series or ammeter in parallel neither of these two marks awarded all symbols correct ignore lines drawn through centres of symbols (c) (i) voltage = current resistance accept V = I R accept volts = amps ohms do not accept V = C R accept if subsequent method correct (ii) 30 Page 6
accept correct substitution for mark (9/0.3) 2 ohms accept correct symbol Ω (iii) goes up must be a comparison accept calculation if answer is larger than c (ii) [] M2. (a) 0.9. accept the value of A 4 + 0.2 (b) V = I R or 2 = 0.6 R or accept V = A R V = I ohm s sign do not credit Ohm s law triangle 2 R = 20 correct numerical answer earns both marks ohms (c) A 3 = 0.3 A 4 = 0.3 accept the same numeric value as A 3 A 5 = 0.5 Page 7
accept the value of A 4 + 0.2 3 [8] M3. (i) power = potential difference current accept voltage for potential difference accept P = V I or correct transposition accept provided subsequent method correct (ii) 8 allow mark for correct substitution or transformation or an answer 2.67 / 2.7 2 [3] M4. level drops as petrol used; causes circuit resistance to increase; causes current to decrease for mark each or if change not specified; (one correct and two vague statements gains 2 marks, three vague statements gains mark) e.g. level changes; ) so resistance changes; ) = mark so current changes ) [3] Page 8