Electronic Control Questions FOR IGCSE PHYSICS
Electronic Control Questions FOR IGCSE PHYSICS
Electronic Control Questions FOR IGCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 1
B
A
om
e.c
A: .......................................................................................................................................................... [1]
B: .......................................................................................................................................................... [1]
ctiv
C: .......................................................................................................................................................... [1]
(b) The current through leg a is 0.12mA and the current through leg B is 2.7mA.
What is the size of the current through leg C?
ma
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
he
(c) The transistor switches off if the current through leg A is low enough.
What effect does this have on the current through leg B?
ww
w.c
..............................................................................................................................................................................
......................................................................................................................................................................... [1]
TOTAL / 6
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 2
ctiv
e.c
om
(a) Draw a circuit in which a lamp comes on if the temperature in the room rises.
[3]
ma
(b) How would you modify your circuit so that the temperature at which the lamp comes on is adjusted?
..............................................................................................................................................................................
..............................................................................................................................................................................
ww
w.c
he
......................................................................................................................................................................... [2]
TOTAL / 5
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 3
A pillar drill in a factory cannot be operated unless a safety screen is down. A circuit diagram for this is shown:
- +
V
om
(b)(i)
Drill on/off
ctiv
B safety screen
on
off
on
off
[4]
ma
A on/off
on
on
off
off
e.c
(a) Complete the table below to show when the drill moter is on or off.
ww
w.c
he
[4]
(ii) What is the name of the logic gate that could be used instead of switches?
......................................................................................................................................................................... [1]
TOTAL / 9
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 4
[1]
om
B
0
Output
0
e.c
ww
w.c
he
ma
ctiv
[4]
TOTAL / 5
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 5
......................................................................................................................................................................... [1]
(ii) Draw up a truth table for a NOT gate.
om
[2]
(iii) What is the purpose of such a gate?
e.c
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
(i)
ctiv
(b) A NAND gate can be made from two other logic gates.
Name the two gates
..............................................................................................................................................................................
ww
w.c
he
ma
......................................................................................................................................................................... [2]
[2]
TOTAL / 8
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 6
input
processor
output
om
..............................................................................................................................................................................
..............................................................................................................................................................................
e.c
......................................................................................................................................................................... [3]
(b) Add to the flow diagram to show feedback.
ctiv
[1]
..............................................................................................................................................................................
..............................................................................................................................................................................
ww
w.c
he
ma
......................................................................................................................................................................... [3]
TOTAL / 7
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 7
The diagram shows a circuit for a burglar alarn. The bell rings when someone stands on the pressure switch.
Wall
Window
Bell
Floor
Relay
om
Pressure
switch
e.c
..............................................................................................................................................................................
......................................................................................................................................................................... [1]
Add a wire to the circuit to enable the bell to continue to ring even through the pressure switch
opens.
ctiv
(b) (i)
[1]
ma
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
he
..............................................................................................................................................................................
ww
w.c
......................................................................................................................................................................... [2]
TOTAL / 6
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 8
and
B
Q
engine
ctiv
Seat belt
switch
e.c
Ignition
switch
om
and
ma
not
alarm
Complete the truth table below to show when the alarm should ring.
P (A and B)
0
he
Input B
0
ww
w.c
Input A
0
Q (Not B)
1
alarm
0
[5]
TOTAL / 7
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 9
A diode is connected in series with a battery and an ammeter. The ammeter registers a current.
battery
diode
ammeter
(a) (i)
om
The diode is then taken out and replaced in the reverse direction.
What, if anything, is observed on the ammeter?
e.c
......................................................................................................................................................................... [1]
(ii) Explain your answer.
ctiv
..............................................................................................................................................................................
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
ma
[3]
[1]
he
..............................................................................................................................................................................
..............................................................................................................................................................................
ww
w.c
..............................................................................................................................................................................
..............................................................................................................................................................................
..............................................................................................................................................................................
TOTAL / 7
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 10
R1
om
R2
e.c
..............................................................................................................................................................................
ctiv
......................................................................................................................................................................... [2]
(b) When the voltage across the base and emitter of the transistor in the circuit is more than 0.6V, it switches on.
(i)
ma
......................................................................................................................................................................... [1]
(ii) What effect does this have on the collector current?
he
..............................................................................................................................................................................
......................................................................................................................................................................... [1]
ww
w.c
......................................................................................................................................................................... [1]
TOTAL / 5
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 11
om
The transistor circuit below uses a resistor and an LDR to form a potential divider.
(a) Describe what happens in this circuit if the LDR is covered up.
e.c
..............................................................................................................................................................................
..............................................................................................................................................................................
ctiv
..............................................................................................................................................................................
......................................................................................................................................................................... [4]
ma
ww
w.c
he
......................................................................................................................................................................... [1]
TOTAL / 5
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 12
An electrician wants to design a circuit for the porch light of a home so that it only comes on when it is dark and
a vistor stands on the doormat.
(a) What sensors should she use?
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
om
(b) She decides that she needs two gates. Name them.
..............................................................................................................................................................................
e.c
......................................................................................................................................................................... [2]
[4]
ww
w.c
he
ma
ctiv
TOTAL / 8
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 13
A central heating system is controlled by a timer mechanism so that the boiler is switched on at specific times.
[2]
e.c
(b) (i)
om
..............................................................................................................................................................................
ctiv
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
ma
..............................................................................................................................................................................
he
..............................................................................................................................................................................
ww
w.c
......................................................................................................................................................................... [3]
TOTAL / 7
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 14
om
......................................................................................................................................................................... [1]
(c) Suggest a suitable output device.
e.c
......................................................................................................................................................................... [1]
ctiv
(d) It would be more efficient if the system could be made to operate a heater.
What changes would be needed to achieve this?
..............................................................................................................................................................................
ww
w.c
he
ma
......................................................................................................................................................................... [3]
TOTAL / 7
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 15
(a) (i)
om
The diagram below shows a simple circuit containing a light-dependent resistor (LDR).
What happens to the resistance of the LDR when light falls on it?
e.c
......................................................................................................................................................................... [1]
(ii) What happens to the voltage across the lamp when light falls on the LDR?
ctiv
......................................................................................................................................................................... [1]
(iii) How can this circuit be modified to tell a blind person that a light has been turned on?
ma
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
(i)
ww
w.c
he
......................................................................................................................................................................... [1]
(ii) Explain why the lights come on as darkness falls.
..............................................................................................................................................................................
..............................................................................................................................................................................
..............................................................................................................................................................................
......................................................................................................................................................................... [3]
TOTAL / 8
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 16
om
(i)
e.c
[2]
ma
ctiv
[2]
he
..............................................................................................................................................................................
ww
w.c
......................................................................................................................................................................... [2]
(b) What components would you need to build a circuit to warn a market gardener that the temperature
of his greenhouse is too low at night?
..............................................................................................................................................................................
..............................................................................................................................................................................
......................................................................................................................................................................... [3]
TOTAL / 9
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 17
[3]
om
e.c
......................................................................................................................................................................... [1]
(ii) the last section
ww
w.c
he
ma
ctiv
......................................................................................................................................................................... [1]
TOTAL / 5
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 18
Name
Symbol
LED
om
Sound
[4]
ww
w.c
he
ma
ctiv
e.c
Motor
TOTAL / 4
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 19
om
..............................................................................................................................................................................
..............................................................................................................................................................................
e.c
......................................................................................................................................................................... [3]
(c) LEDs, which are used for digital displays are long and thin.
How many of these LEDs are needed to display all the numbers from 0 to 9?
ctiv
(i)
......................................................................................................................................................................... [1]
[2]
ww
w.c
he
ma
(ii) Draw the numbers 4 and 6 as they would appear in an LED digital display.
(iii) Explain why the number eight always shows when the digital display is changing rapidly.
..............................................................................................................................................................................
......................................................................................................................................................................... [2]
TOTAL / 9
GCSE PHYSICS
ELECTRONIC CONTROL
QUESTIONSHEET 20
iron reeds
What will you see when a magnet is brought near the reed switch?
ctiv
(i)
e.c
om
......................................................................................................................................................................... [1]
(ii) What will happen when the magnet is moved away again?
(b)(i)
ma
......................................................................................................................................................................... [1]
How can a reed switch be used as part of a burglar alarm?
he
..............................................................................................................................................................................
..............................................................................................................................................................................
ww
w.c
......................................................................................................................................................................... [3]
(ii) How can a reed switch be used to turn the power off when a microwave door is opened?
..............................................................................................................................................................................
..............................................................................................................................................................................
......................................................................................................................................................................... [3]
TOTAL / 8