Work Package 3

Question 1

how does an LDR work?

Answer 1

the resistance changes according to the amount of light shining directly on it.

Question 2

in darkness, what happens to an LDR resistor?

Answer 2

in darkness, its resistance rises to about 10M

Question 3

in bright light, what happens to an LDR resistor?

Answer 3

in bright light, its resistance falls to about 1 K

Question 4

are LDRs polar or non-polar?

Answer 4

non-polar

Question 5

if the Vout is high and light intensity increases, what happens to the Vout?

Answer 5

the Vout changes from high to low

Question 6

if the Vout is low and light intensity decreases, what happens to the Vout?

Answer 6

the Vout changes from low to high

Question 7

what is Vout?

Answer 7

voltage out

Question 8

how does a thermistor work?

Answer 8

its resistance changes according to temperature. It converts changes in temperature into changes in electric current.

Question 9

what is the most popular type of thermistor?

Answer 9

the negative coefficient type. Its resistance decreases as it gets hotter

Question 10

are thermistors polar or non-polar?

Answer 10

non-polar

Question 11

if the Vout is high and the temperature increases, what happens to the Vout?

Answer 11

the Vout changes from high to low.

Question 12

if the Vout is low and the temperature decreases, what happens to the Vout?

Answer 12

the Vout changes from low to high

Question 13

what is a PIC controller also called?

Answer 13

a computer in a chip

Question 14

what can a PIC controller be programmed to do?

Answer 14

to respond to input devices and control output devices.

Question 15

when PIC microcontrollers run programmes, what voltages do they run them between?

Answer 15

3V and 5.5V d.c.

Question 16

what is a voltage regulator?

Answer 16

electricity regulation device designed to automatically convert voltage into a lower, usually direct current (DC), constant voltage.

Question 17

what are the 6 different sized PICAXE PIC microcontrollers?

Answer 17

1. 8 pin
2. 14 pin
3. 18 pin
4. 20 pin
5. 28 pin
6. 40 pin

Question 18

what are two facilities that PICAXE microcontrollers have built into them?

Answer 18

1. analogue to digital conversion (ADC)

2. infra-red

Question 19

what does a flowchart show?

Answer 19

the order in which a series of commands are carried out

Question 20

what are the two states of digital signals?

Answer 20

1. high, which equals 1

2. low, which equals 0, therefore it cant use the decimal system of counting, which uses 10 digits.

Question 21

what is a binary system?

Answer 21

a system in which information can be expressed by combinations of the digits 0 and 1

Question 22

what is a bit and what is a byte?

Answer 22

a bit is the binary digits 0 and 1. Eight bits make one byte.

Question 23

what does MSB and LSB stand for?

Answer 23

MSB - most significant bit

LSB - least significant bit

Question 24

what does the sensor in an analogue system do?

Answer 24

the sensor generates a voltage which then controls something. E.g. a heating system.

Question 25

what does the sensor in a digital system do?

Answer 25

the sensor sends pulses/ clicks. E.g. these clicks may then switch a heating system on or off.

Question 26

what is the processor in a microcontroller system called?

Answer 26

a PIC (peripheral interface controller) (programmable intelligent computer)

Question 27

how many transistors does a PIC in a microcontroller system have?

Answer 27

20000 to 100000 transistors