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 Young's modulus of a material?
If a wire loop moves at constant speed into a region where there is a magnetic field, why is a current induced in the wire?
From the 2016 OCR B paper A ball is thrown at an angle of 30 Degrees to the horizontal. The initial kinetic energy of the ball is K. Air resistance is negligible. What is the kinetic energy of the ball at the maximum height.
A phone is knocked off a table 800cm of the ground. If the phone is 650g a) what is the gravational potential of the phone? b)what speed will the phone hit the floor at? c)How long will it take for the phone to hit the floor?