Which of the statements are true, If a convex lens is placed in water:
a. Its focal length increases.
b. Its focal length decreases.
c. Rays bend less when they move through lens.
d. There is no change in radius of curvature.
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A ray of light strikes a glass plate at an angle of \(60^{\circ}\). If the reflected and refracted rays are perpendicular to each other then the refractive index of glass is

Two antennas A and B have maximum line of sight range R = 45.5 km. If the height of antenna A is 32 m then the height of antenna B is : (Given radius of earth is = 6400 km)

A light bulb and an air core inductor are connected in series to an a.c. source through a switch. The switch is closed and after sometime, an iron rod is inserted into the interior of the inductor. The light bulb

In cyclotron, an ion is made to travel successively along semi circles of increasing radius under the action of magnetic field. Which of the following factor on which angular velocity of the ion is not dependent?

Which of the following statements are correct?
(A) The electrostatic repulsive force between the protons can be greater than the nuclear force to bind the nucleons together inside a nucleus.
(B) The repulsive electrostatic force between protons in smaller nuclei is much smaller than the nuclear force between nucleons inside a nucleus.
(C) The gravitational force between nucleons is much smaller than the nuclear force between the nucleons inside a nucleus.
(D) The binding energy per nucleon between nucleons is almost constant because the nuclear force is a long range force.
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Choose the correct statements:
A. In uniform electric field E, the net force on electric dipole is zero.
B. The torque on dipole in electric field is \( \tau = PE \cos \theta \), where \( \theta \) is angle between \( \vec{P} \) and \( \vec{E} \).
C. In non uniform Electric field, when dipole moment P is parallel to E, the dipole has a net force in the direction of decreasing field.,
D. The direction of torque is perpendicular to both \( \vec{P} \) and \( \vec{E} \).
E. The net torque is zero if E is not uniform.
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When a ray of light is incident on the face AB of prism normally, after refraction it is found to graze the side AC as shown in the figure, the refractive index of the prism is

2, 4, 6 - trinitrophenol is
[Structure: Phenol ring with \(- NO _2\) groups at positions 2, 4, and 6]

Two nuclei have mass numbers 125 and 27, respectively. The mass density ratio of their nuclei will be

Bt toxin is expressed in plants to provide resistance to insects; hence used as a bio-pesticide. Select the correct examples of Bt plants:
(A). Bt Cotton
(B). Bt Rice
(C). Bt Peas
(D). Bt Corn
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The angular momentum of an electron in the third orbit of a hydrogen atom is (Given \( h = 6.6 \times 10^{-34} \text{ J s} \))

Which of the following acts as bio fertilizer in paddy field?