1
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

In the Young's double slit experiment $$n^{\text {th }}$$ bright for red coincides with $$(n+1)^{\text {th }}$$ bright for violet. Then the value of '$$n$$' is: (given: wave length of red light $$=6300^{\circ} \mathrm{A}$$ and wave length of violet $$=4200^{\circ} \mathrm{A}$$).

A
2
B
4
C
3
D
1
2
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

A metal ball of $$20 \mathrm{~g}$$ is projected at an angle $$30^{\circ}$$ with the horizontal with an initial velocity $$10 \mathrm{~ms}^{-1}$$. If the mass and angle of projection are doubled keeping the initial velocity the same, the ratio of the maximum height attained in the former to the latter case is :

A
1 : 2
B
2 : 1
C
1 : 3
D
3 : 1
3
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

The threshold frequency for a metal surface is '$$n_0$$'. A photo electric current '$$I$$' is produced when it is exposed to a light of frequency $$\left(\frac{11}{6}\right) \mathrm{n}_{\mathrm{o}}$$ and intensity $$\mathrm{I}_{\mathrm{n}}$$. If both the frequency and intensity are halved, the new photoelectric current '$$\mathrm{I}^1$$' will become:

A
$$\mathrm{I}^1=\frac{1}{4} \mathrm{I}$$
B
$$\mathrm{I}^1=2 \mathrm{I}$$
C
$$\mathrm{I^1=0}$$
D
$$\mathrm{I}^1=\frac{1}{2} \mathrm{I}$$
4
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

A $$500 \mathrm{~W}$$ heating unit is designed to operate on a $$400 \mathrm{~V}$$ line. If line voltage drops to $$160 \mathrm{~V}$$, the percentage drop in heat output will be:

A
74%
B
85%
C
84%
D
75%
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