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 ▸An electron is moving with speed 2x10^5ms-1 through a magnetic field of strength 0.5T. If the electrons velocity is perpendicular to the direction of the magnetic field, what is the magnitude of the force felt by the electron?
What is the Centripetal force, and how does it keep objects in circular motion?
A nail of mass 7.0g is held horizontally and is hit by a hammer of mass 0.25kg moving at 10ms^-1. The hammer remains in contact with the nail during and after the blow. (a) What is the velocity of the hammer and nail after contact?
Describe the interaction that is responsible for keeping protons and neutrons together in a stable nucleus.