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 ▸What is the Photoelectric effect?
A block of ice slides down the full height from one side of a 1m high bowl and up the other side. Assuming frictionless motion and taking g as 9.81ms-2, find the speed of the block at the bottom of the bowl and the height it reaches on the the other side.
A passenger is standing in a train. The train accelerates and the passenger falls backwards. Use Newton's first law of motion to explain why he fell backwards.
What is the difference between plastic and elastic collision?