1
VITEEE 2024
MCQ (Single Correct Answer)
+1
-0

The primary of a transformer has 400 turns while the secondary has 2000 turns. If the power output from the secondary at 1000 V is 12 kW . The resistance of the primary is $0.2 \Omega$ and that of the secondary is $2 \Omega$. If the efficiency of the transformer is $80 \%$, then the power loss in the primary is

A
288 W
B
1125 W
C
2000 W
D
725 W
2
VITEEE 2024
MCQ (Single Correct Answer)
+1
-0

The maximum power rating of a $20 \Omega$ resistor is 2 kW . Then, it cannot be used with 300 V DC source because the

A
current drawn is very large and it can blow the fuse.
B
current drawn is very less and appliance does not work.
C
resistor may melt due to excessive heat.
D
None of the above
3
VITEEE 2024
MCQ (Single Correct Answer)
+1
-0

A metal surface is illuminated with photons of energies $E_1=4 \mathrm{eV}$ and $E_2=2.5 \mathrm{eV}$ respectively. The ratio of maximum speeds of the photoelectrons in two cases is 2 . Work function of metal surface will be

A
2.5 eV
B
5 eV
C
4 eV
D
2 eV
4
VITEEE 2024
MCQ (Single Correct Answer)
+1
-0

A germanium crystal is doped with arsenic atoms and indium atoms simultaneously. Number of arsenic atoms used $=5 \times 10^{22}$ per $\mathrm{m}^3$ and number of indium atoms used $=5 \times 10^{20}$ per $\mathrm{m}^3$, then resulting crystal is a/an

A
p-n junction
B
p-type semiconductor
C
$n$-type semiconductor
D
Depends on number of germanium atoms in given sample.
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