1
JEE Main 2024 (Online) 4th April Morning Shift
+4
-1

An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is $$25 \mathrm{D}$$. Focal length of each of the convex lens is:

A
50 cm
B
20 cm
C
25 cm
D
500 cm
2
JEE Main 2024 (Online) 4th April Morning Shift
+4
-1

In an experiment to measure focal length ($$f$$) of convex lens, the least counts of the measuring scales for the position of object (u) and for the position of image (v) are $$\Delta u$$ and $$\Delta v$$, respectively. The error in the measurement of the focal length of the convex lens will be:

A
$$2 f\left[\frac{\Delta \mathrm{u}}{\mathrm{u}}+\frac{\Delta \mathrm{v}}{\mathrm{v}}\right]$$
B
$$f\left[\frac{\Delta \mathrm{u}}{\mathrm{u}}+\frac{\Delta \mathrm{v}}{\mathrm{v}}\right]$$
C
$$f^2\left[\frac{\Delta \mathrm{u}}{\mathrm{u}^2}+\frac{\Delta \mathrm{v}}{\mathrm{v}^2}\right]$$
D
$$\frac{\Delta \mathrm{u}}{\mathrm{u}}+\frac{\Delta \mathrm{v}}{\mathrm{v}}$$
3
JEE Main 2024 (Online) 31st January Morning Shift
+4
-1

The refractive index of a prism with apex angle $$A$$ is $$\cot A / 2$$. The angle of minimum deviation is :

A
$$\delta_m=180^{\circ}-3 \mathrm{~A}$$
B
$$\delta_m=180^{\circ}-4 A$$
C
$$\delta_m=180^{\circ}-2 A$$
D
$$\delta_m=180^{\circ}-A$$
4
JEE Main 2024 (Online) 29th January Evening Shift
+4
-1

If the distance between object and its two times magnified virtual image produced by a curved mirror is $$15 \mathrm{~cm}$$, the focal length of the mirror must be:

A
$$-10$$ cm
B
$$-12$$ cm
C
15 cm
D
10/3 cm
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