What will be the number of photons emitted per second by a 10 W sodium vapour lamp assuming that 90% of the consumed energy is converted into light [Wavelength of sodium light is 590 nm, and h = 6.63×10-34 J –s]
What will be the number of photons emitted per second by a 10 W sodium vapour lamp assuming that 90% of the consumed energy is converted into light [Wavelength of sodium light is 590 nm, and h = 6.63×10-34 J –s]
Subtopic: Photoelectric Effect: Experiment |
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200 MeV of energy may be obtained per fission of U235. A reactor is generating 1000 kW of power. The rate of nuclear fission in the reaction is
Subtopic: Nuclear Energy |
53%
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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 emf, 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-
1. E increases
2. I increases
3. Q remains same
4. Q decreases
2. I increases
3. Q remains same
4. Q decreases
Subtopic: Faraday's Law & Lenz Law |
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Which one of the following is not made of soft iron?
1. Electromagnet
2. Core of transformer
3. Core of dynamo
4. Magnet of loudspeaker
Subtopic: Magnetic Materials |
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Two tangent galvanometer having coils of the same radius are connected in series. A current flowing in them produces deflection of 60 ° and 45 ° respectively. The ratio of the number of turns in the coils is
+1)/2
/1
+1)/(
-2)
Subtopic: Moving Coil Galvanometer |
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A bar magnet of magnetic moment 104 J/T is free to rotate in a horizontal plane. The work done in rotating the magnet slowly from a direction parallel to a horizontal magnetic field of 4×10-5 T to a direction of 60 ° from the field will be
Subtopic: Bar Magnet |
60%
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An ideal coil of 10 H is joined in serried with a resistance of 5 Ω and battery of 5 V, 2 s after joining the current flowing (in ampere) in the circuit will be
Subtopic: LR circuit |
58%
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A rocket is fired upward from the earth surface such that it creates an acceleration of 19.6 m/s2. If after 5 s, its engine is switched off, the maximum height of the rocket from earth’s surface would be
1. 245 m
2. 490 m
3. 980 m
4. 735 m
Subtopic: Distance & Displacement |
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A 60 kg weight s dragged on a horizontal surface by a rope through a distance of 2m. If coefficient of friction is μ=0.5, the angle of rope with surface is 60 ° and g =9.8 m/s2, then work done is
1. 294 J
2. 15 J
3. 588 J
4. 197 J
2. 15 J
3. 588 J
4. 197 J
Subtopic: Friction |
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A small uncharged metallic sphere is positioned exactly at a point midway between two equal and opposite point charges. If the sphere is slightly displaced towards the positive charge and released then
1. it will oscillate about its original position
2. it will move further towards the positive charge
3. its electric potential energy will decrease and kinetic energy will increase
4. its total energy remains constant but is non-zero
Subtopic: Electric Potential Energy |
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