A normal eye is not able to see objects closer than 25cm because:
Explanation:
The ciliary muscles adjust the focal length to form an image on the retina, but the muscles cannot be strained beyond a limit. Hence, if the object is brought too close to the eye, the focal length cannot be adjusted to form the image on the retina.
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Two positive charges of 20 coulomb and Q coulomb are situated at a distance of 60 cm. The neutral point between them is at a distance of 20 cm from the 20 coulomb charge. Charge Q is
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(a) 30 C |
(b) 40 C |
(c) 60 C |
(d) 80 C |
Assertion : The force with which one plate of a parallel plate capacitor is attracted towards the other plate is equal to square of surface density per e per unit area.
Reason : The electric field due to one charged plate of the capacitor at the location of the other is equal to surface density per e.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
If 
is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity when the slit width is doubled
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(a) |
(b) |
(c) 2 |
(d) 4 |
Work function of a metal is 2.1 eV. Which of the waves of the following wavelengths will be able to emit photoelectrons from its surface
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(a) 4000 Å, 7500 Å |
(b) 5500 Å, 6000 Å |
(c) 4000 Å, 6000 Å |
(d) None of these |
Consider telecommunication through optical fibres. Which of the following statements is not true
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(a) Optical fibres may have homogeneous core with a suitable cladding |
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(b) Optical fibres can be of graded refractive index |
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(c) Optical fibres are subject to electromagnetic interference from outside |
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(d) Optical fibres have extremely low transmission loss |
The incident photon involved in the photoelectric effect experiment.
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(a) Completely disappears |
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(b) Comes out with an increased frequency |
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(c) Comes out with a decreased frequency |
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(d) Comes out without change in frequency |
Pick out the longest wavelength from the following types of radiations
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(a) Blue light |
(b) g-rays |
(c) X-rays |
(d) Red light |
A current carrying rectangular coil is placed in a uniform magnetic field. In which orientation, the coil will not tend to rotate
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(a) The magnetic field is parallel to the plane of the coil |
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(b) The magnetic field is perpendicular to the plane of the coil |
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(c) The magnetic field is at 45o with the plane of the coil |
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(d) Always in any orientation |
