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 ▸3 resistors, R1, R2 and R3 are attached in parallel across a 6V cell with resistances 3, 4 and 5 Ohms respectively. Calculate the current across each resistor.
the moon takes 27.3 days (2.36x10^6s) to orbit the earth . Calculate its distance from the earth . Take the mass of the earth to be 5.975x10^24kg.
Can you talk me through how to solve problems on projectiles? I always get confused
A transmitter from a researcher's boat sends a signal to the seabed of waves speed 300m/s and it takes 5 seconds for the signal to return back to the boat. Calculate the depth of the sea there.