Electronics

Question 1

Ohms law

Answer 1

/ V \

/ I | R\

Question 2

AC current

Answer 2

Alternate current

Flows in different directions. Used to supply power to houses.

Question 3

DC current

Answer 3

Direct current
Flows in one direction.
Used in batteries, household electronics

Question 4

Function of a transformer

Answer 4

It is used to maintain a current of electricity by transferring energy between two or more circuits.

Question 5

What is a voltage rectifier?

Answer 5

Converts AC to DC

Question 6

Darlington pair

Answer 6

Two transistors linked together to amplify current.

Question 7

Function of Capacitors and examples of where it’s used. Units

Answer 7

Capacitors store energy for a period of time.
They are used in camera flashes, computer emergency shut down, AC to DC conversions.
Unit: farad

Question 8

Give examples of inputs, processes and outputs.

Answer 8

Input- LDR, thermistor, switch
Process- microchip, transistor, resistor, genie board
Outputs- led, bulb, buzzer, relay

Question 9

With the aid of a diagram list the characteristics of an led.

Answer 9

Has two legs.
Anode-longer and positive.
Cathode-shorter and negative.
Flat edge on negative side

Question 10

How to identify a resistor

Answer 10

4 colour bands. 
1st colour- first no.
2nd colour- second no.
3rd colour-no. of 0s
4th colour-+/- 10%-silver /5%-gold

Question 10

How to calculate voltage across a potential divider setup.

Answer 10

Voltage across R1:
R1
—— X Source Voltage
R1+R2

Question 11

How to calculate resistors in parallel

Answer 11

1 = 1 + 1
—– —- —-
Rtotal R1 R2

Question 11

Calculating Resistors in series

Answer 11

Rtotal =R1+R2+R3…..

Question 13

Advantages and disadvantages to wiring in parallel

Answer 13

Adv: If one bulb breaks the rest work. All receive equal amounts of current.
Dis: Depletes battery quickly

Question 14

What is a relay and examples of where used.

Answer 14

A relay is an electro-magnet switch that links a low power circuit to a high power circuit.
It can be used in a sensor circuit that triggers a large motor.

Question 16

Forward voltage

Answer 16

The maximum voltage required to light an led. (Vf)

Question 17

Note!!

Answer 17

The intensity of current flow (amps) is dependant on the voltage source. The bigger the voltage the bigger the current and vice versa.
The bigger the resistance, the bigger the voltage must be to push the current through it.

Question 18

What measures the voltage, current and resistance and how is it connected to the circuit.

Answer 18

Voltage: Voltmeter, wired in parallel
Current: Ammeter, wired in series
Resistance: Ohmmeter

Question 19

How to wire a DPDT switch.

Answer 19

X across at sides and battery connection in middle

Question 20

Potential divider setup.

Answer 20

High: sensor on top, resistor on bottom
Low: sensor on bottom, resistor on top

Question 21

Draw a relay circuit for detecting high water levels which switches on a motor.

Answer 21

Probes at top. Transistor, two resistors, diode, relay, motor

Question 22

Transistor formula

Answer 22

Current gain= Ic/Ib

Ratio between the current going in (base) and the current going out (collector)

Question 23

What is a solenoid

Answer 23

An electrical device that converts electrical current into movement in a straight line. Used in a relay.

Question 24

Function of a Diode

Answer 24

Prevents excess current generated by larger circuit getting back into the sensitive sensor circuit..
Prevents back EMF (an electric kickback) being generated.