A.M. WEDNESDAY, 19 May minutes

Transcription

1 Candidate Name Centre Number Candidate Number 0 GCSE 293/02 ELECTRONICS MODULE TEST E1 HIGHER TIER AM WEDNESDAY, 19 May minutes For s use Total Mark ADDITIONAL MATERIALS In addition to this examination paper you may need a calculator INSTRUCTIONS TO CANDIDATES Write your name, centre number and candidate number in the spaces at the top of this page Answer all the questions in the spaces provided in this booklet INFORMATION FOR CANDIDATES The number of marks is given in brackets at the end of each question or part-question SJJ*(S )

2 INFORMATION SHEET This information may be of use in answering the questions 1 Resistor Colour Codes BLACK 0 BROWN 1 GREEN 5 BLUE 6 The fourth band colour gives the tolerance as follows: RED 2 VIOLET 7 GOLD ± 5% ORANGE 3 GREY 8 SILVER ± 10% YELLOW 4 WHITE 9 2 Preferred Values for Resistors E 12 SERIES OF PREFERRED VALUES 10; 12; 15; 18; 22; 27; 33; 39; 47; 56; 68; 82 and multiples thereafter 3 Resistance = voltage current ; R = V I 4 Effective resistance, R, of two resistors R 1 and R 2 in series is given by R = R 1 + R 2 5 Effective resistance, R, of two resistors R 1 and R 2 in parallel is given by R = RR 1 2 R1 + R 2 6 Voltage Divider + V S R 1 R 2 V OUT = R R 2 + R 1 2 V S 0V 7 Power = voltage current; 2 2 V P = VI = I R = R 8 LED The forward voltage drop across an LED is 2V 9 Transistors (i) Current gain = Collector current Base current IC ; h FE = I B (ii) The forward voltage drop across the base emitter junction is 0 7V

3 3 Answer all questions in the spaces provided 1 Here is a list of electronic components: thermistor LED variable resistor LDR (a) Which component from the list has this symbol? Answer (b) Which component from the list would you use to sense a change in light level? Answer Turn over

4 4 2 The LED in the following circuit has a current of 10 ma and forward voltage drop of 2 V across it 6 V 10 ma 2 V R 0 V (a) Calculate how much power is used in the LED (b) (i) What is the current through resistor R? (ii) What is the voltage across resistor R? (c) Use the formula in the information sheet on page 2 to calculate a suitable resistance for resistor R (d) Choose a suitable preferred value for resistor R from the E12 series in the information sheet on page 2 so that the LED has no more than 10 ma flowing through it

5 5 3 The resistor colour code is given in the information sheet on page 2 (a) Here is a diagram of a 8200 Ω resistor Write the colours in the boxes on the diagram below Band 1: Band 3: Band 2: [3] (b) Here is a diagram of another resistor R Band 1: Red Band 3: Orange Band 2: Violet tolerance band: Gold (i) Use the colour code to work out the value of the resistor R Resistance in ohms = (ii) What is the percentage tolerance of the resistor R? Turn over

6 6 4 (a) The diagram shows a comparator IC seen from above A B (i) Give the pin number of the pin labelled A (ii) Give the pin number of the pin labelled B (b) Here is part of a comparator circuit : +12 V R 1 10 kω R 2 30 kω V 1 V 2 V OUT 0 V (i) Use the equation given in the information sheet to calculate the voltage V 1

7 7 (ii) The output V OUT of the comparator saturates at + 12 V and 0 V Resistors R 1 and R 2 are now changed so that V 1 becomes 60 V Complete the table for the given values of V 1 and V 2 V 1 (V) V 2 (V) Output V OUT (V) Is LED on or off? (c) A sensing sub-system is now connected to the comparator so that the LED is on when it is light Complete the diagram below to make: (i) the voltage at input Y high when it is light, (ii) the voltage at the inverting input adjustable [4] +12 V R 1 R 2 Y 0 V Turn over

8 8 5 The block diagram shows a design for a car alarm The alarm is set by pressing a push switch on the remote control If someone opens a door, a micro switch operates and the buzzer sounds Block A Block B Block C Buzzer Push switch on remote control (a) Here is a list of sub-systems: temperature sensing unit AND gate pulse unit comparator transistor switch / transducer driver micro switch Which sub-system is: (i) suitable for block A? (ii) suitable for block B? (iii) suitable for block C? [3] (b) This system would not make a very good alarm (i) Explain what the main problem would be with this system (ii) Name an additional sub-system which is needed to correct this fault (iii) Put an X on the diagram above to show where you would place this subsystem

9 9 6 The following circuit diagram shows part of a system used to switch on a bulb 6 V 6 V, 60 ma R B h FE =200 0 V V 1 V 2 V 3 The transistor is just saturated when the input voltage V 1 is 21 V (a) Complete the following table to show: the voltage V 2 and V 3 for the input voltages V 1 given whether the bulb will be On or Off V 1 V V VV V 3 Bulb On/Off? [5] (b) V 1 = 21 V and the transistor is just saturated The transistor in this circuit has a current gain h FE of 200 The collector current through the lamp is 60 ma (i) Calculate the base current through R B (ii) Calculate the voltage drop across R B (iii) Calculate the resistance of R B END OF QUESTION PAPER