1. I don’t know which way to put the batteries in my rear LED bike light. Which
ID: 1425936 • Letter: 1
Question
1. I don’t know which way to put the batteries in my rear LED bike light. Which of the 2 diagrams above represents the correct way to install the battery?
A) 1 B) 2 C)Neither
2. What type of light does an LED produce?
a. White photons
b. Visible light of all wavelengths
c. Light of basically one wavelength determined by the energy jump between conduction and valence bands
3. If I increase the current through an LED light, what changes occur?
Light gets brighter and whiter
Light gets brighter and redder in color
Light gets brighter but no change in color
No change in light output but the LED gets hotter
No noticeable change
4. Think about the way that an LED light produces light and compare to the way that an incandescent bulb and an atom produces light. Which is the LED more similar to? And why?
My answer is ACC, are they correct? thanks for explain
A)Light gets brighter and whiter
B)Light gets brighter and redder in color
C)Light gets brighter but no change in color
D)No change in light output but the LED gets hotter
E)No noticeable change
Explanation / Answer
Here,
Part A:
LEd is Pn junction so P = + and n = -
so 2 option si correct
Part B:
When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons.
so option (C) is correct
Part C:
As LED drive currents increase for multiplexing, internal temperatures within the LED also increase.
There is a point at which the temperature increase causes a drop in photon conversion efficiency, which, in turn, negates the effect of the increased current density through the junction.
At this point, increasing drive currents can result in a small increase, no change, or even decrease in light outputs from the LED chip.
so option D is correct
Part D:
LEd are similar to atoms as incandacent bulb work simply on filament of wire when heated to high temperature it glows in presence of halogen gas.
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