प्रकाशिकी

Which of the following statements are correct?

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Which of the following statement(s) is/are correct?

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In an experiment with a convex lens, the length of an image is $1\,\text{cm}$, and the object length is $5\,\text{cm}$. If the object is placed at a distance of $40\,\text{cm}$ from the lens, then the focal length of the lens is:

The critical angle of incidence $i_c$ for a ray incident from a denser to rarer medium, is that angle for which:

Which of the following statements are correct?

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If focal length of a concave lens is $50\,\text{cm}$, then the power of the lens would be:

A curved surface $APB$ of radius of curvature $10\,\text{cm}$ separates air ($n_1 = 1$) and a transparent material ($n_2 = 4/3$). A point object $O$ is placed in air on the principal axis of the surface $20\,\text{cm}$ from the pole $P$. The surface is concave towards the rarer medium (center of curvature lies in air, $R = -10\,\text{cm}$). The distance of the image of $O$ from $P$ will be ____________.

For fixed values of radii of curvature of a lens, the power of the lens will be _________________.

The graph correctly representing the variation of image distance $v$ for a convex lens of focal length $f$ versus object distance $u$ is represented by a rectangular hyperbola having asymptotes at $u = f$ and $v = f$ (Option 2).

The refractive index of the material of an equilateral prism is $\sqrt{2}$. The angle of minimum deviation of that prism is _____________.

Lower half of a convex lens is made opaque. Which of the following statement describes the image of the object placed in front of the lens?

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For an astronomical telescope having objective lens of focal length $10\,\text{m}$ and eyepiece lens of focal length $10\,\text{cm}$, the telescope's tube length and magnification respectively are _____________.

Light is travelling from one medium to another medium as given in the options. In which of the following options total internal reflection will be possible?

An astronomical telescope consists of an objective of focal length $50\,\text{cm}$ and eyepiece of focal length $2\,\text{cm}$ is focused on the moon so that the final image is formed at the least distance of distinct vision ($25\,\text{cm}$). Assuming angular diameter of moon as $(1/2)^\circ$ at the objective, the angular size of image is:

A spherical air lens of radii $R_1 = R_2 = 10\,\text{cm}$ is cut from a glass ($\mu = 1.5$) cylinder as shown in the figure. Its focal length is $f_1$. If a liquid of refractive index $2$ is filled in the space, then the focal length of the liquid lens becomes $f_2$. Calculate $f_1$ and $f_2$. Choose the correct options from the following:

Linear magnification produced by a mirror is $+1.5$. Which of the following is correct?

The graph shows the variation of the magnification ($m$) produced by a thin lens with image distance ($v$). The focal length of the lens is:

If a light ray travels from a denser to a rarer medium, which of the following statement/s are correct ?

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To increase magnifying power of a refracting type Telescope, we should increase :

The radius of curvature of the curved surface of a plano-convex lens is 20 cm. If the refractive index of the material of the lens be 1.5, then the focal length of the lens will be :

A boy of height 1 m stands in front of a convex mirror. His distance from the mirror is equal to the focal length of the mirror, the height of the image is :

In a Young's double-slit experiment, two slits are $1.5\,\text{mm}$ apart while the screen is $1.2\,\text{m}$ away. When a light of wavelength $600\,\text{nm}$ is incident on the slits, the fringe width will be:

A polaroid sheet is rotated between two crossed polarizers. The intensity of transmitted light would be maximum, when the angle between the axes of the first polarizer and the polaroid sheet is:

Using light from a monochromatic source to study diffraction in a single slit of width $0.1\,\text{mm}$, the linear width of central maxima is measured to be $5\,\text{mm}$ on a screen held $50\,\text{cm}$ away. The wavelength of light used is _______________.

Two slits are made $0.1\,\text{mm}$ apart and the screen is placed $2\,\text{m}$ away. The fringe separation when a light of wavelength $500\,\text{nm}$ is used is ____________.

A slit of width $e$ is illuminated by light of wavelength $\lambda$. What should be the value of $e$ to obtain the first maximum at an angle of diffraction of $\frac{\pi}{3}$?

In Young's double slit experiment, yellow light of wavelength $640\,\text{nm}$ produces fringes of width $0.8\,\text{mm}$. What will be the fringe width if the light source is replaced by another monochromatic source of wavelength $720\,\text{nm}$ and the separation between the slits is made thrice?

The type of wavefront that emerges from a distant light source is:

Case based

The British physicist Thomas Young used an ingenious technique to lock the phases of the waves emanating from two coherent sources $S_1$ and $S_2$. As these sources were derived from same source symmetrically placed with respect to $S_1$ and $S_2$, the phases of waves were same. If any abrupt change happens in original sources, it will manifest exactly similar phase changes in the light coming out of two sources $S_1$ and $S_2$. Due to constructive interference and destructive interference at different points in space and screen alternate dark and bright fringes of equal width were obtained. This pattern was called an interference pattern. The width of each band was equal with central fringe as bright fringe.

The phase difference ($\Delta\phi$) between two superimposing waves to obtain constructive interference and hence bright band, is :

If two sources of intensities $I_0$ each have a randomly varying phase difference $\phi$, the resultant intensity at centre of screen will be :

In Young's double slit experiment, an interference pattern is obtained on the screen. If one of the slits is closed, then :

In Young's double slit experiment, the separation between the slits is halved and distance between the slits and screen is doubled. The fringe width will be :

In Young's double slit experiment, the fringe width is 0.4 mm. If the whole apparatus is immersed in water of refractive index $\frac{4}{3}$, without changing its geometry, the new fringe width will be :