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 ▸Using Newton's law of gravitation, derive a suitable formula for the escape velocity of an object at Earth's surface.
A box is pulled with a rope at 26° to the horizontal and a tension of 120N. What is the work done in pulling it 5 metres?
If a car is travelling over a curved hill, what is the maximum speed it can travel before losing contact with the road surface?
A ball of mass 0.7 kg strikes the wall at an angle of 90 degrees with speed 72 km/h. Consider that the bounce lasts for 0.1 s and is perfectly elastic. What is the magnitude of the average reaction force from the wall that acts on the ball?