night lamp
TRANSCRIPT
FSNSYou only learn by doing it yourself
From Scrap and Scratch
Experiment 1
Night Lamp
Materials Required
i. Bread Board
ii. Resistor: 220k ohm , 330 to 1000 ohm
iii. 9V Transistor Battery - 1
iv. Connecting Wire
v. LDR
vi. NPN transistor
vii. LED
Step 1
Take a Breadboard
Step No.2
Connect a 9V Battery on the breadboard
Step No.3
Connect a NPN transistor on the breadboard with its 3 pins( emitter base and collector) in 3 different holes
on the breadboard
Step No.4
Connect LDR between base of transistor and ground and connect emitter to ground
Step No.5
Connect a resistor of 220k ohm between base and Vcc(power supply)
Step No.6
Connect a combination of LED and a resistor between collector and Vcc. The LED doesn’t glow.
Step No.7
Now when we cover LDR with a black surface,LED glows
Reasoning
Covering the LDR increases the resistance and hence the potential at base increases thereby providing enough voltage to the base emitter junction to switch on.
An LDR as you must have studied in level 1 has resistance between 10 to 70k ohm. We are using this property of LDR to make our night lamp.
FSNSYou only learn by doing it yourself
From Scrap and Scratch