Prepared by G. C. Accom

SOME OF THE SYMBOLS WE WILL USE
SYMBOL NAME
SWITCH
BULB
TRANSISTOR
BUZZER
SYMBOL NAME
LDR
RESISTOR
CAPACITOR
DIODE
CELLS IN
PARALLEL
CELLS IN
SERIES

How to make a simple cell-holder for batteries
USE A
PIECE OF
RUBBER
HOSE AND
A KNIFE

CUT A SLIT INTO THE HOSE

SLIDE THE NUMBER OF CELLS YOU
NEED INTO THE SLIT YOU HAVE CUT

I GRADE 9 YOU WILL BE WORKING WITH
THE FOLLOWING POWER SOURCES
EXPLAIN TO
LEARNERS
WHY WE SAY
THESE CELLS
ARE
CONNECTED
IN SERIES

A SIMPLE CIRCUIT WITH CELLS
CONNECTED IN SERIES
SWITCH MADE WITH PAPER CLIP AND THUMB TACK
PUSH SWITCH
ALWAYS ON
TOGGLE
SWITCH
PUSH SWITCH
ALWAYS OFF

PUSH SWITCH Normally ON in its normal state

It switches OFF when you press it

PUSH SWITCH Normally OFF in its normal state

It switches ON when you press it

CIRCUIT DIAGRAM FOR TWO CELLS
CONNECTED IN SERIES

SWITCH OPEN

SWITCH CLOSED

CELLS CONNECTED IN PARALLEL
Switch Open

CELLS CONNECTED IN PARALLEL
Switch Closed

BULBS CONNECTED IN SERIES

SEE WHAT HAPPENS WHEN ONE BULB
IS REMOVED

BULBS CONNECTED IN PARALLEL

SEE WHAT HAPPENS WHEN ONE BULB
IS REMOVED

AND SWITCH – Both Open

AND SWITCH – One Closed

AND SWITCH – Both Closed

OR SWITCH – Both Open

OR SWITCH – Bottom switch closed

OR SWITCH – Top switch closed

OR SWITCH – Both switches closed

4,5 v battery, switch, resistor and LED

CIRCUIT DIAGRAM

LDR, buzzer, 3v battery

Buzzer sounds when light of torch is brought close

CIRCUIT DIAGRAM

LDR with LED

LED is ON in absence of LIGHT

LED is OFF in presence of LIGHT

CIRCUIT DIAGRAM

Circuit with switch, resistor, capacitor, diode & LED
NOTE- LED is OFF

NOTE- LED is ON

NOTE POWER SUPPLY IS REMOVED
BUT - LED is still ON

CIRCUIT DIAGRAM

TOUCH OR MOIST DETECTOR
SWITCH OPEN = LED OFF
WATER

SWITCH CLOSED = LED ON
WATER

CIRCUIT DIAGRAM

YOU CAN USE EXACTLY THE SAME
CIRCUIT TO ADD A BUZZER
CONNECT TERMINALS OF BUZZER HERE
WATER