1
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
LED is constructed from Ga-As-P semiconducting material. The energy gap of this LED is 1.9 eV. Calculate the wavelength of light emitted and its colour.

[h = 6.63 $$\times$$ 10$$-$$34 Js and c = 3 $$\times$$ 108 ms$$-$$1]
A
654 nm and orange colour
B
654 nm and red colour
C
1046 nm and red colour
D
1046 nm and blue colour
2
JEE Main 2021 (Online) 25th February Evening Shift
+4
-1
For extrinsic semiconductors; when doping level is increased;
A
Fermi-level of both p-type and n-type semiconductors will go upward for T > TFK and downward for T < TFK, where TF is Fermi temperature.
B
Fermi-level of p-type semiconductor will go upward and Fermi-level of n-type semiconductors will go downward
C
Fermi-level of p and n-type semiconductors will not be affected.
D
Fermi-level of p-type semiconductors will go downward and Fermi-level of n-type semiconductor will go upward.
3
JEE Main 2021 (Online) 25th February Evening Shift
+4
-1
The truth table for the following logic circuit is :

A
B
C
D
4
JEE Main 2021 (Online) 25th February Morning Slot
+4
-1
A 5V battery is connected across the points X and Y. Assume D1 and D2 to be normal silicon diodes. Find the current supplied by the battery if the +ve terminal of the battery is connected to point X.

A
$$\sim$$ 0.5 A
B
$$\sim$$ 1.5 A
C
$$\sim$$ 0.43 A
D
$$\sim$$ 0.86 A
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