A biconvex lens forms a real image of an object placed perpendicular to its principal axis. Suppose the radii of curvature of the lens tend to infinity. Then the image would
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(a) Disappear |
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(b) Remain as real image still |
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(c) Be virtual and of the same size as the object |
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(d) Suffer from aberrations |
(c) Be virtual and of the same size as the object
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As shown in the figure, a magnet is moved with a fast speed towards a coil at rest. Due to this induced electromotive force, induced current and induced charge in the coil is E, I and Q respectively. If the speed of the magnet is doubled, the incorrect statement is
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(a) E increases |
(b) I increases |
(c) Q remains same |
(d) Q increases |
A wire of resistor R is bent into a circular ring of radius r. Equivalent resistance between two points X and Y on its circumference, when angle XOY is a, can be given by
|
(a) |
(b) |
(c) R (2 p – a) |
(d) |
If the following input signal is sent through a PN-junction diode, then the output signal across RL will be
(a)
|
(b)
|
(c)
|
(d)
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The current in the given circuit is
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(a) 0.1 A |
(b) 0.2 A |
(c) 0.3 A |
(d) 0.4 A |
A metallic surface with work function of 2 eV, on heating to a temperature of 800 K gives an emission current of 1 mA. If another metallic surface having the same surface area, same emission constant but work function 4 eV is heated to a temperature of 1600 K, then the emission current will be
|
(a) 1 mA |
(b) 2 mA |
(c) 4 mA |
(d) None of these |
In a dark room of photography, generally red light is used. The reason is
|
(a) Most of the photographic films are not sensitive to red light |
|
(b) The frequency for red light is low and hence the energy hv of photons is less |
|
(c) (a) and (b) both |
|
(d) None of the above |
A thermocouple of resistance 1.6Ω is connected in series with a galvanometer of 8Ω resistance. The thermocouple develops and e.m.f. of 10 μV per degree temperature difference between two junctions. When one junction is kept at 0℃ and the other in a molten metal, the galvanometer reads 8 millivolt. The temperature of molten metal, when e.m.f. varies linearly with temperature difference, will be
|
(a) 960℃ |
(b) 1050℃ |
(c) 1275℃ |
(d) 1545℃ |
The path of a refracted ray of light in a prism is parallel to the base of the prism only when the
|
(a) Light is of a particular wavelength |
|
(b) Ray is incident normally at one face |
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(c) Ray undergoes minimum deviation |
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(d) Prism is made of a particular type of glass |
