Describe one technique you could use to measure the threshold voltage for LEDs.
A sensitive ammeter is placed in series with LED. With the increase in Voltage, measure the potential difference value when it starts conducting. Black-out and shaded vision tube is used to observe the voltage value when visible light is first observed as the voltage is increased.
MP
Related Physics A Level answers
All answers ▸When red light is shone on a metal, regardless of the intensity of this light, no current will flow. However if blue light is shone on this metal a current will flow. Why does this occur?
Explain what happens in terms of current induced as a magnet enters a solenoid in a closed circuit, and as it leaves.
In a particle accelerator, you accelerate an electron. Afterwards, you measure it's energy to be 350 keV. Tell my why you can't find the speed from this energy using your knowledge of classical mechanics.
Why is Kinetic Energy mv^2/2?