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 ▸A student studied how a few parameters of the electromagnetic radiation affects the I-V(current-voltage) curve of photoelectricity. By increasing one parameter he saw that the saturation current has risen. Which parameter it was?
Why are values for gravitational potential always negative?
2 identical trolleys of mass M(one is loaded with 2 blocks of mass m) are on a ramp inclined at 35° and are connected by a wire that passes around a pulley at the top of the ramp. They are released and accelerate accordingly. Show that a=(mgsin35°)/(M+m).
Describe how a PET scan works?