Circuits

Question 1

Battery

Answer 1

Provides power to the circuit

Question 2

Battery snap

Answer 2

Used to connect the battery to the circuit

Question 3

Slide switch

Answer 3

Turns the circuit on an off

Question 4

Resistor

Answer 4

1. Reduces the current flow
2. Forms a potential divider

Question 5

Light dependent resistor( LDR)

Answer 5

Change resistance as light levels rise and fall

Question 6

Transistor

Answer 6

Switches the outputs on and off

Question 7

Light emitting diode (LED)

Answer 7

Outputs light

Question 8

Buzzer

Answer 8

Outputs sound

Question 9

What do you need to do

Answer 9

Learn ALL the circuits symbols

Question 10

How do you read a resistor

Answer 10

1st band=1st digit
2nd band=2nd digit
Last band= number of zeros

Band on right hand end=tolerance band

Question 11

What are the colours numbers for a resistor

Answer 11

Black=0
Brown=1
Red=2
Orange=3
Yellow=4
Green=5
Blue=6
Violet=7
Grey=8
White=9

Question 12

What is ohm’s law

Answer 12

Ohm’s law describes the relationship between voltage, current and resistance and can be calculated using the triangle

Question 13

V

Answer 13

Voltage measured in volts

Question 14

R

Answer 14

Resistance measured in Ohms

Question 15

I

Answer 15

Current measured in Amps

Question 16

Describe ohms triangle

Answer 16

i x r =V
v/i=R
v/r=I

Question 17

What are transistors

Answer 17

Transistors are a type of high speed electronic switch. Instead of pressing s button we must send a signal of 0.7 volts to the base leg

Question 18

What are transistor usually protected by

Answer 18

A resistor at the base

Question 19

Name the parts of a transistor on a symbol

Answer 19

middle line=base
Diagonal straight line=collector
Diagonal arrow=emmiter

Question 20

What is a potential divider

Answer 20

Potential dividers are part of a circuit which is made up of two resistors in a line between positive and negative rails and are used in circuits to adjust voltage

Question 21

What is v.out

Answer 21

The voltage out between the two resistors in a potential divider.
The value of the voltage out depends on the value of the resistors.

Question 22

If both resistors are the same

Answer 22

V.out will be half v.in
E.g. 9v in means 4.5v out

Question 23

If the top resistor has a large valence

Answer 23

It will use most of the voltage and then we will have less than half at v.out

Question 24

If the top resistor has a small value

Answer 24

It uses little voltage and we will have more than half at v.out

Question 25

Describe the potential dividers diagram

Answer 25

Positive rail at the top is v.in Point between two resistors is v.out Negative rail at the bottom

Question 26

Describe the LDR in light

Answer 26

Has a high resistance in the dark and a low resistance when its bright

Question 27

LDR

Answer 27

light dependent resistor

Question 28

Describe the LDR on a light alarm circuit in the dark

Answer 28

-the slide switch is closed(on) -the LDR resistance is high -V.out is very small -the transistor does not get 0.7v to the base leg -the outputs are switched off

Question 29

Describe the LDR on a light alarm circuit in the light

Answer 29

-the slide switch is closed(on) -the LDR resistance is low -V.out is big -the transistor get 0.7v to the base leg -the LED switches on -the buzzer sounds

Question 30

Why would you have a LDR in light alarm circuit

Answer 30

So that when daylight hits the alarm would sound

Question 31

What is a PCB

Answer 31

A PCB is a printed circuit board. The board is made from a non-conductive material(fibreglass/plastic) that has conductive pathways etched or printed onto its surface. They are usually made from copper

Question 32

What is soldering

Answer 32

Soldering is a process used to join electronic components to a PCB by melting a filler metal (solder) to create a strong electrical and mechanical bond between the components leads and the conductive traces on the board

Question 33

How would you make a light alarm circuit outputs switch on in the dark without adding any new components

Answer 33

Switch the position of the LDR and fixed resistor so that the LDR is at the bottom

Question 34

What two ways can you identify the negative side of LED

Answer 34

-negative leg is shorter -flat side of a bulb shows negative side

Question 35

What do you need to solder

Answer 35

Soldering iron to melt filler metal(solder) Wet sponge to clean iron in between soldering