1
WB JEE 2024
MCQ (Single Correct Answer)
+1
-0.25

If $$\hat{n}_1, \hat{n}_2$$ and $$\hat{\mathrm{t}}$$ represent, unit vectors along the incident ray, reflected ray and normal to the surface respectively, then

A
$$\hat{n_2}=\hat{n_1}-2\left(\hat{n_1} \cdot \hat{t}\right) \hat{t}$$
B
$$\hat{n}_2=\hat{n_1}+2\left(\hat{n_1} \cdot \hat{\mathrm{t}}\right) \hat{\mathrm{t}}$$
C
$$\hat{\mathrm{n}_2}=-\hat{\mathrm{n}_1}$$
D
$$\hat{n_2}=2 \hat{n_1}-\left(\hat{n_1} \times \hat{\mathrm{t}}\right) \cdot \hat{n_1}$$
2
WB JEE 2024
MCQ (Single Correct Answer)
+2
-0.5

When a convex lens is placed above an empty tank, the image of a mark at the bottom of the tank, which is 45 cm from the lens is formed 36 cm above the lens. When a liquid is poured in the tank to a depth of 40 cm, the distance of the image of the mark above the lens is 48 cm. The refractive index of the liquid is

A
1.353
B
1.544
C
1.472
D
1.366
3
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25

Three identical convex lenses each of focal length $$\mathrm{f}$$ are placed in a straight line separated by a distance $$\mathrm{f}$$ from each other. An object is located at f/2 in front of the leftmost lens. Then,

A
Final image will be at f/2 behind the rightmost lens and its magnification will be $$-1$$.
B
Final image will be at f/2 behind the rightmost lens and its magnification will be $$+1$$.
C
Final image will be at f behind the rightmost lens and its magnification will be $$-1$$.
D
Final image will be at f behind the rightmost lens and its magnification will be $$+1$$.
4
WB JEE 2022
MCQ (Single Correct Answer)
+1
-0.25

The human eye has an approximate angular resolution of $$\theta$$ = 5.8 $$\times$$ 10$$-$$4 rad and typical photo printer prints a minimum of 300 dpi (dots per inch, 1 inch = 2.54 cm). At what minimal distance d should a printed page be held so that one does not see the individual dots?

A
20.32 cm
B
29.50 cm
C
14.59 cm
D
6.85 cm
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